How can i lose the weight?

I am 15 years old,5'5 and weigh 121 pounds and would like to be under 110 pounds,preferably by september.I have tried loads of stuff but can't seem to find anything that works. I rarely eat junk food and eat healthy(once a week at most)and don't drink soda drinks,only water.How can i lose the weight?Please help me,i know i'm not overweight but i feel uncomfortable with my weight and have started to hate going out and dislike shopping because i end up feeling bad about myself. I will do anything to lose the weight and no i'm not talking about amputating my arm off or barfing my guts out so don't get angry.Anyway thanks.