It sounds like you're doing okay about redirecting her during non meal times. However, she needs to have at least 3 snacks a day as well as 3 meals.
Right now she may be experiencing a growth spurt and will need the extra healthy nutrients to build strong bone and muscle. All of my boys turned into food monsters that could not get full between 2 and 4. We've seen major growth in all of them at that time too.
As for cutting back on fats in milk. It's important that you cut back on fats in other dairy products as well so check the fat content and limit her to 24 ounces of dairy a day.
Since she's so tall, you really can't limit her weight that much, and remember that muscle weighs much more than fat so as you walk you're going to be building those muscles and he weight is going to go up.
The only other thing I could suggest is watching her calories and talking her into lower calorie snack and meals. If this means you cut out the rice, pasta, corn and potatoes for a while that will be okay.
Remember to serve her on a child sized plate and she has to finish everything to recieve 2nds. You should not be giving her portions any larger than the palm of her hand. That's ya'lls portion size too and when you're done, walk away from the table. That will discourage her from wanting 2nds.
Get outside, get moving.