First of all, the baby needs the fat in whole milk. Is she active? Does she spend a lot of time watching videos, etc?
I'm a 49 year old mother of 22 and 14 year old girls, and I am currently raising my 2 year old grandbaby girl. Here is a sample of her diet:
Daily: Oatmeal. Not the packages, and not quick oats. Easy to make, 1/4 cup oats, 1/2 cup milk, pop into the microwave at 50% power for six minutes. I add a little butter or a little applesauce to it. She loves it, and it keeps her full for a long time.
Lunch...I slice an orange (and take it out of it's peel) or an apple, or maybe cut a banana in half, and give her that first. After she's eaten the fruit, I'll give her some cheese and maybe some yogurt. The dairy products are really important for many reasons, you can look that up online. I give her fruit juice, which I make from frozen and I always add an extra can of water. At dinner, I give her the veggies first, peas, for instance, and then I'll give her some mac n cheese or some rice, she really likes refried beans and rice. She eats pretty much whatever her auntie (my teen) and I eat, just in smaller portions. If I make burgers, she has a smaller burger. Baked potato is great. If I make (whole wheat, not enriched) pasta and alfredo or red sauce, that's what she eats. She likes the canned ravioli, I'll give her that, about 1/3 of a can at a meal. Sometimes I'll give her a scrambled egg or two for lunch or dinner. I give her sandwiches occasionally, but not too often. And cheap bread is horrible! The snacks are fine, but the main thing I'd suggest is making sure she gets enough exercise. Take her out for a walk, no stroller! It sounds like you are able to be home with her. Turn on some music and dance with her. And make sure she is taking a kiddie vitamin every day to make up for any nutrients she may miss.
I would also suggest that you not get too excited. I have had issues with my weight all my life too, but that is because of the way I EAT and not being willing to get enough exercise. When I eat right and get enough exercise, I'm okay. Don't visit your weight issues on the baby. If her size 2Ts are fitting her properly, you probably have nothing at all to worry about. And if she is tall, no reason why size 3T shouldn't fit her with a little room. Kids generally grow up, then out, then up, then out, and so on.