I'll put my 2 cents in here since I still feel like I'm 20...
The best thing you can do for yourself is to STOP looking at those magazines until you're ready to accept the way you are. Sure, we want and need to stay healthy, but the fact of the matter is that you were made this way and that is that.
Right now, the stick figure may seem appealing to you, but ask any man (NOT BOY) out there and they will say that they like a woman with a butt and hips.
If you start with healthy habits now, it will be so easy to keep them going throughout your life.
DON'T count calories like a mad woman, weigh yourself, or do any of that. Make healthy choices and you will just naturally eat within your means. Easy ways to cut calories- water instead of soda, wheat instead of white bread, fruit instead of candy, eating 6 times a day instead of big meals, eating a handful of something (like dry roasted peanuts without salt) and NOT half the container, eating at home instead of out, having a piece of chocolate instead of a whole Snickers bar. It's hard at first, trust me. But you will start to crave those good foods.
Remember that you're eating this way not to be skinny, but to be HEALTHY! Notice how much better your clothes look rather than staring at a scale. Go for a walk instead of watching TV. And most of all, accept and love yourself because confidence will make anyone look their best.