Help me stop please and give me other solutions.

Tumbles600

Hi I am a 14 year old girl weighing about 174 pounds. I do not understand why I am obese as I hardly eat and have sports while at school 5 days a week, in fact I probably eat less than the rest of my friends who weigh less, I do not understand why, is there something wrong with me? I do not like looking in the mirror and seeing what I see. I am not being bullied nor am depressed or committing self harm and would not consider myself a 'loner'. I say all of this to show that what I am doing is for me because if I don't change myself now while I still can, I will live a sad hard life, enough of that now. I have started a healthy lifestyle and exercising regularly for 30min, 4 days a week. I have a bad tendency of not eating but surprisingly NOT feeling the urge to binge later on and this makes me feel good, I am sad to admit this.I then go on further and exercise until my kneecaps feel as though they're collapsing, I can't stop. Help me please.