Eat a well balanced diet and get plenty of exercise. That will get you to where your body should be ~ fit and healthy. Everyone is lazy ~ wants to pop pills, throw up, do strange diets, but the truth is, the only way to lose weight and keep it off and be healthy is to eat smart and exercise 3 - 5 times a week.
You may not realize this, but you are beautiful exactly the way you are right now. The people who love you, the people that are good for you, always see how very beaiutiful you are. Those are the people you want in your life. Anyone that thinks you are not perfect the way you are is a person not worth bothering with. Just be healthy, Sweetie. Be healthy in body and mind. And take JKGrandma's advice and see someone about those destructive thoughts you have about yourself. When you say that you want to be extremely thin, what you are really saying is "I want to kill myself." Get some help soon.