Reluctantly Weaning

I suggest that you nurse him first and then let him eat solids. He needs the milk until he's a year old. Milk should be his primary source of nutrition. His body is not mature enough to adequately process solids. Not enough milk may be the reason his weight is so low as to not be on the chart.

Perhaps you mean he's past the 100th percentile. That's not healthy either.

My daughter weaned herself off nursing by 11 months. She had been drinking some formula at daycare for several months, so I switched to that and then whole milk. I would rather feed formula than worry the baby wasn't getting enough milk. Goals are fine, but your baby's needs are more important, and he's on his own schedule.

My suggestions are:

Offer the breast before giving solids. Do not just give solids, always ensure his belly has some good Mommy Milk first.

Offer the breast OFTEN thru-out the day

Allow quiet time with background white noise and im lights (if possible) during the nursing times.

The thing is, some babies wean themselves.

But for the 1st year of life, breastmilk/Formula IS a baby's PRIMARY source of nutrition. Not solids and not other liquids. And to still, nurse on-demand. Not according to a schedule.
And to nurse baby, BEFORE giving solids. Otherwise, a baby will be too full to nurse, after solids or with solids.
And then the baby, will wean from breast.
For the 1st year, if possible, the focus is nursing. Because, solids is not as nutritionally dense... as solids.

Anyway, so your milk is decreasing.
If you want it to increase, then put him to breast more often.
Unless he just flat-out rejects you.

My kids had GINORMOUS appetites, as babies. I nursed on-demand always.... 24/7 and night. Sure, they had solids introduced from 6 months old... but the focus for me was breastfeeding. Not the solids. And I did not give my kids 3 meals a day of solids, from the get go. Only once a day. Then over the course of the year, gradually worked up to, 3 times a day of solids.
But again, my focus was still, nursing on-demand, PRIMARILY. Not solids.
And, my kids grew like weeds, and were always in the upper 97-98th percentiles on the growth charts, but were very lean, and they gained weight on par.

I guess, your son is noticing the diminished milk output, from you too.
Thus, does not nurse so much.

Ask your Pediatrician.
You said... that your baby is low on the weight-charts.

My son self-weaned at about 1 year old.
My daughter self-weaned at about 2.5 years old. Yes, I chose to do self-weaning for my kids.

Well, I've always been a fan of letting the child lead in letting you know when he's hungry and feeding on demand. I've also been in favor of child-led weaning.

I had a different issue in that I always had supply problems from day one with each of my breastfed babies. My youngest daughter nursed the longest, but it was frustrating for her and she let it show even at five months. He weight dropped and she wasn't ready for solids. We couldn't boost my supply no matter what I did, and I even did a weekend nurse-in.

I ended up giving her formula and I don't regret it because she drank it down so ravenously and as if it were the most delicious thing she ever had. Her weight started to increase as it should have been. We supplemented for the next month but she showed a clear preference at that point and refused the breast. She even preferred pacifiers. There was no nipple confusion, there was no solid food getting in the way... I just had supply problems. By eight months old or so she was ready for daily solids rather than just tastes of food here and there.

As for your son, at 10 months old and with what you described as to how much table food he eats, have you considered reducing the amount of solids he eats for a while? Most of his nutrition "should" be coming from either breastmilk or formula right now and table food or pureed foods should only be for "practice" and not for nutrition. It sounds to me like he's eating too much in the way of solids and the only way to boost your supply back up will be to have him be hungry enough to nurse frequently for entire meals and build your supply back up. I would personally only give him solids AFTER having had his fill of breastmilk or formula.

Let him nurse as long as he wants. It seems like he is eating way too much table foods if he's out eating two adults. Cut back on the food a little, and its ok if he only nurses morning and night and before naps, thats ok for a 10 mo old. Your milk will adjust. It becomes thicker, more concentrated and more dense. he's getting what he needs, just cut back on the table foods a little nad make sure what he's eating is healthy, and he will do great. I wouldn't bother with formula at this point unless he stops nursing completely.

I suppose I have an alternative perspective about breast milk. Yes I think its great for boosting immunity and mother's should alway be encourage/supported to breastfeed. However, my motto about it is: Breast milk is only as good as the mother's own diet. There's nothing wrong with giving him formula--especially since he's no longer a newborn and eating solids. Formula will ensure that he's getting the required protein, vitamins and essential fats (for brain development), especially as he enters the picky eater stage.

On a related topic, you mentioned that your son is underweight even though he is a good eater. Have you considered that he may have a food allergy? If he is allergic to something even though he is eating well, then that could explain why he isn't gaining weight; its possible that his intestines are irritated (from the allergen) and that in turn interferes with them absorbing all food. He eats & eats & eats (because his body is hungry), but he's not absorbing the nutrition.

My daughter was born in the 90th percentile for weight and then over her first year, she fell to the 25%. Slow decline at first, then steady around the 50%; then, she fell significantly to 25%, then 20%. I could not get her to gain weight. I fought for every ounce and felt so defeated when I'd take her back for a check-up, convinced that she must have gained something after all the effort I'd put in her diet, only to find she hadn't gained anything. I feed her the most calorie intensive diet I could think of... butter and cheese on everything, followed her around with food every 2 hours. Kept her on toddler formula (doctor's orders) even when she was over 1 year. Her pediatrician even said I must be "feeding her too healthy" and told me to give her ice-cream three times a day.

My daughter had a food allergy. That was why she didn't gain weight. Once the allergen was completely removed from her diet, her weight started to go up. She's now in the 55% for weight. But I have to admit it was hard to see her shorter than her classmates. I really wanted her to be in the same general height as other kids her age. It took a good 2 years (plus a constant focus on her eating more healthy than the average kid), but she is now the same height as her peers. She's still skinny, but at least her clothes size match her age (as in, she wasn't wearing size 3 when she was a 4 yr.)

I was so stressed out about trying to get y daughter's weight up (in addition to her having chronic sinus and congestion issues, that were related to the food allergy). I wish someone had mentioned the possibility of it to me when she was 10 months old and saved me the heartache of having to find it all out on my own. Your son might not have a food allergy. Some kids are just small, but still healthy. But I had to mention it, since I walked that path.

Good luck (and don't stress over the formula).

I really wanted to nurse longer too, but both my kids weaned at about that age. Don't beat yourself up about it, if he's done with it. 10 months is a good solid amount of time and he might just be ready for table food supplemented by formula.

Many of the groups I follow for breastfeeding suggest nursing before table food. You are only 2 months shy a year so don't beat yourself up about it...you've done great so far.
If you want to nurse longer, increase your nursing sessions, or add a pump session...