My dd will be 3 in September and right now she weighs around 25 pounds. She is 36 inches tall. We have been going to a nutritionist at Childrens memorial for awhile now and we get regular weight checks at the peds office. She still nurses although it's only 2 to 6 times a day depending on her desire. Here's what they have told me and it seems to be working for my dd. She's really started adding some good weight and now even has sorta round thighs.
I can still see her ribs though and that makes me nervous too. So first off, they don't worry if her weight doesn't go up a lot just so long as she is still getting taller. Secondly they had me stop her from grazing all day. My kiddo doesn't get enough calories that way but yours could be different. We eat on a lenient schedule so that way she can get hungry and eat a nice amount at one time. Of course toddlers have little tummies so it's an every 3 hour or so schedule. Our schedule goes like this: 9am we eat breakfast, 12 we have lunch, 3 a snack, 6 we eat dinner and before bed a nice big snack around 9 pm. It works because she recognizes her body telling her it's hungry and if she's hungry at 11:30 instead of noon then that's when we eat, kwim. We just had this nasty cycle of me panicking b/c she didn't eat enough and then I'd offer a snack and she would be full at the next meal and here's mom going "oh my, she won't eat! Have another snack!" It's easy to panic when they are such little peanuts to begin with.
The other thing I've done is to increase calories everytime she eats. I add a cup of nonfat dry milk to her half gallon of whole milk, I add oil to everything, I use Udo's Oil in her yogurts to help with omega 3's, I use a lot of nut butters and even sneak them into smoothies or shakes for her, avacados are great too for sneaking into stuff. The doctor prescribed pediasure but my dd doesn't care too much for them and has to be in the mood or she won't drink them. You can pretty much use them anywhere you would milk though. I make her oatmeal with it sometimes.
She doesn't consume a ton but she's getting a better appetite recently. I really just try to make every meal count and add the calories.
As far as the nursing, I don't know what to tell you. Her docs don't know she still nurses but that's b/c they are not supportive of it at all. I cried in the room when one of the specialist told me that I was going to have to wean dd right then b/c 1 and a half years was long enough and I'd made my point.
It was time to give her food and cows milk to make her grow. I don't agree but I don't feel like fighting the battle everytime I go there so what they don't know won't hurt them! (or dd!) I don't know how demanding your toddler is to nurse but I try to have mine stick to after she's had her meals and she's ok with it.
Best of luck mama and feel free to pm me.