I really want to know how to get a girls tummy, but I really don't know how, I am 20 yo beginning sissy, and I'd love to be more pretty. The thing holding me back most about being a sissy is that I feel like it is real hard to look convincingly like a girl.
Your body is made in the kitchen. If you can, see if you're able to go to a Nutritionist or Dietician and build out a plan to achieve your goals. This will get you at least 80% of the way if you can maintain the strict diet. Unless they're kink informed or whatever just say that you want to slim down and lower your body fat to be slender but not be super ripped or anything.