You're stomach may not be a weight issue, it may just be the place your body stores its fat. Even when I was nice and skinny I always had a giggly pot on my tummy. If you are worried you will get obsessed with your weight, talk to your doctor about how to maintain it in a healthy way. Also, remember, you are 15 - your body is changing drastically. Your weight and shape last year was probably very different than it is this year and it will be different again next year. As long as your doctor feels your weight is safe for your size, you need to focus on that and not your shape. I know that is hard in your teen years... it wasn't long ago I was a teen. The social pressures to look a certain way are very difficult. But health is key. You need a certain amount of body fat in order to develop properly. Ever see those female athletes who have so little body fat that they are shaped like little boys? You don't want that! It is possible that fat will move to other places as you grow. Best of luck!