My stepdaughter Heba – who was already grown when I came into her life – always teases me: How old’s that kid again? Olivia’s 3-1/2, as Heba well knows, and, yes, she still nurses before bed and upon waking. From what I can tell, it seems to be the ultimate in comfort food, and while Olivia may not need it anymore, she loves using it to transition from wakefulness to sleepiness and back again. I don’t know when we’re going to stop.

Heba’s question never fails to make me laugh. An inside joke, it refers to a trailer she and I happened to see together in the movie theater for the 2010 comedy Grown-Ups (as with so many movies, the trailer is much funnier than the film). The trailer features a kid who walks over to his mom, who’s seated at a lawn party and announces, “Mommy, I want some milk.” She says, “Come here, baby,” adjusts her V-neck dress, and pulls him to her breast. The boy then nurses standing up. One guest, hand over her own young daughter’s eyes, says, “Your son’s so cute. How old is he again?” The boy’s father says, with forced brightness, “48 months!” Another guest exclaims, “That’s four!”

Heba sometimes sends me links to what she calls “creepy” YouTube videos showing older children breastfeeding with the implicit warning: Don’t let this happen to you! One of these, “Extraordinary Breastfeeding,” is a short documentary by Channel Four in the U.K. about a mother who believes children should be allowed to self-wean. One of her two daughters, Bethany, had stopped a few years earlier, at age seven, and the other, nearly eight at the time of filming, would still nurse occasionally.

The girls are shown drawing pictures of their mother’s breasts and referring to them by their nicknames: for the right one, which the girls said had “more milk,” Milkior; and for the less abundant, Boobior. Heba’s philosophy on all this is, if a kid is old enough to ask for milk – never mind naming the breasts – she’s old enough to drink only the kind you get from the supermarket.

My own sense of what’s too old keeps creeping upward. Before Olivia learned to walk, a friend related a story about a three-year-old niece who was still nursing and who would apparently walk right up to her mother and suddenly lift up her shirt to nurse, even in public. Yikes, I thought. Three! That’s too old for breastfeeding! These days I look at the girls in the Channel Four documentary and think, Seven! Whoa, that’s way too old. But what is the right age to cut a child off, and why? If I don’t have a compelling reason – social disapproval doesn’t really work, since I’ve long since gone underground and become a closet nurser – it’s hard to imagine standing firm through the inevitable tears. When Olivia wants “Mommy milk” and is afraid she isn’t going to get it, she lets out a cry that’s different from any other I’ve heard – more piteous, more primal. It cuts through me.

There’s a name for what I would like to do: child-led weaning. At this moment, though, my daughter shows little inclination to lead me in that direction. When I ask her when she’s going to stop, and tell her that her friends at school don’t do it anymore (which I don’t actually know, but I assume), she laughs and says “Pretty soon.” Her laugh has a maniacal edge to it, and I suspect she’s thinking, Never!

In terms of simple nutrition, Olivia can certainly do without my milk. On any given day, she also eats baked chicken, French fries, lima beans, saut’ed mushrooms, strawberries, you name it. You’ll fill her up and spoil her appetite, people warn me. A Google search for “calories” and “breastmilk” suggests that there are about 20 calories in one ounce. I remember how long it took me to pump an ounce back when she was small and I wanted to freeze some, just in case. The quantity of milk that my body produces now, having adjusted on its own to fit what she uses, is a fraction of what it was then when she was exclusively breastfed. I doubt she gets more than two ounces in one sitting, and I can’t see how 40 calories (less than half the calories in a mini-box of raisins) could ruin her appetite for “real food.”

The benefits of breastmlk are well known and include strengthening the immune system, providing protection from illness, and helping the brain, gut, and other organs to develop. Several researchers have specifically argued that these protective effects extend well beyond infancy and apply to nursing toddlers, as well. Physician Jack Newman actually suggests that breastmilk may contain more protective factors during the baby’s second year of life than the first, which is fitting, he says, since “children older than a year are generally exposed to more infection.” The World Health Organization recommends that mothers nurse exclusively for six months, and then continue until “two years or beyond,” supplementing breastmilk with appropriate foods.

There are benefits to mothers, too: Breastfeeding helps protect against breast and ovarian cancer, helps women lose weight and keep it off, and may lessen the risk of osteoporosis and hip fractures later in life. But as Newman also points out, all of these are fringe benefits. He writes about extended breastfeeding, “Possibly the most important aspect of nursing a toddler is not the nutritional or immunologic benefits, important as they are. I believe the most important aspect of nursing a toddler is the special relationship between child and mother. Breastfeeding is a life-affirming act of love. This continues when the baby becomes a toddler.”

Olivia doesn’t nurse to unconsciousness, so surely I’m not keeping her from learning to “self-soothe” or settle down and go to sleep. We have a routine: We read a book while nursing on one side, then flip and read another book. We pick the books right beforehand. Each book – I always advocate for short ones like Mercer Meyer’s Just a Daydream or I Just Forgot – only takes a couple of minutes to read. When we’re done, she walks over to her bed and climbs in.

I don’t always like breastfeeding. Olivia wakes at 6:30 a.m. like clockwork, and often I listen to the slamming of her door, followed by quick footsteps and the opening and slamming of our door, and then a long succession of quick footsteps, with a slight sense of dread. I’m too tired to embark on a half-hour of lying flat on my back in our bed while Olivia clings and crawls and twists my hair into snarls. Sometimes she simply won’t stop, and I have to enlist the help of a third party – my husband – to “pull this vampire bat off me.”

Obviously, many women wean children earlier for a lot of different reasons. They may have to go back to work outside the home and find it difficult or unappealing to pump milk there. They may just want their bodies back. They may have had a hard time with nursing from the start.

But with the help of a good lactation consultant, breastfeeding came easily to me. It’s true that at this point, stopping would make my life easier – I would be able to go away for the whole night, if I wanted to. A week even. At the same time, I will be a little sad when we do stop, whenever that may be. Breastfeeding makes me feel not just important but crucial; it’s something only I can do for her.

In fact, my stepdaughter’s objections seem to include an unspoken suspicion that breastfeeding is really all about me. Breastfeeding until a kid is three or four is all well and good for people in developing countries, but here we’ve got real food! So why make her keep doing it? She doesn’t actually say, You must be pretty needy yourself. It’s true that Olivia’s an only child for all intents and purposes, and that I don’t plan to have any more. My husband and I married in mid-life, and we were lucky to have Olivia when I was in my forties.

But I don’t believe I’m trying to stretch out her infancy to satisfy some unhealthy longing of my own. It’s not about longing, but savoring. I savor the innocent way that she expresses a hunger for me that goes far beyond the physical, and the private moments when we express our connection so literally. Childhood is a fleeting time, and while I’m not trying to stretch it out beyond all reason, I’m not trying to catapult her toward adulthood either.

I have few memories of cuddling with my own mother. Back in the late 1960s and early 1970s, mothering was a much less hands-on business than it is today. Mothers basically figured they’d given you life; now you could figure out what to do with yourself until dinner. Sometimes I feel like a little more cuddling might have made me less uncertain, less anxious to prove myself as I was growing up.

Now I find myself telling Olivia, “You’re a big girl, all grown up, and you don’t really need Mommy milk anymore.” She agrees completely. “I’m a big girl now. I don’t need it. I’m going to stop drinking Mommy milk. Pretty soon.” Then she laughs and tugs at my shirt and settles in to nurse once more, drinking deeply and quietly and twirling my hair.

I know that any decision to wean needs to be firm. Once I start withholding milk from her, my body will start to produce less, so I won’t be able to easily change my mind. Once I step off that cliff, I need to be sure.

Here’s the main reason I still nurse her. Child development researchers believe in “implicit memory” – that while young children may not have explicit memories of events from the first few years of life, they do have implicit memories. It’s in the implicit memory bank that trauma, for instance, or neglect are stored. I hope that one thing Olivia will take from this dreamlike period of childhood is a general sense of well-being. Not a sense of entitlement. Just a sense of confidence that the world means her well.