Re: 16 month old, slow weight gain. Any advice??
I haven't personally had experience with a slow-to-gain toddler, but I still think I can answer some of your questions, based on what I have read here, posted by moms who have had issues with their kids being tiny or slow to grow.
The first thing to check is the scale. Using different scales at different well-baby visits can really throw off where your child falls on the chart, and whether that makes growth appear normal, or not. Even in the second year, children should be weighed on the same scale every time and in the nude- particularly if they are petite.
Second thing to think about is her growth in height and head circumference. If she is continuing to grow along a reasonable trajectory in those dimensions, it's a good indicator that she's getting enough to eat and is growing at her own, unique trajectory, and is just going through a pause in her weight gain. Growth isn't perfectly smooth in all dimensions, after all- it's pretty normal for kids to pause in height and shoot up in weight, or to pause in weight while growing significantly taller.
It's also normal for the rate of weight gain to slow waaaay down in the second year. Kids grow fastest in infancy and then slow down in toddlerhood. For example, my kids gained around 10 lbs in their first 4-6 months, but didn't gain another 10 lbs until around 18 months, and their third 10 lb increment took at least another year, probably more- and my kids are off the charts for height and on the high side for weight.
Your baby has always been petite, and that's a good indicator that her weight is normal. But your doc's course of action makes sense to me- take a wait-and-see approach for now, while focusing on her diet and trying to get her to eat some more high-calorie solids. If her weight gain doesn't pick up in a few months, maybe consider some tests to rule out possible non-normal explanations for slow growth- I think you'd be looking at some hormone tests and maybe some allergy tests, as well. Nothing too invasive or crazy.
Pediasure is one way to get calories into a toddler, but there are other, arguably healthier alternatives- like adding olive oil or butter to her low cal solids (e.g. veggies, cereals, and fruits), or just giving her some ice cream!
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"