Is something wrong with me?

First of all, I am a 13 year old girl. (In my answers or other questions it may say I'm 22 cuz my sister Rachelle uses my account sometimes) I eat a lot, but I don't get fat. I like healthy foods, but sometimes I am just have extreme cravings for sweet things, which my mum refuses to buy. It sometimes get so bad that I either a.) Go to a friends house and eat, or b.) Gorge myself with cheese sticks and unsalted potato crisps, the only somewhat junkfood my mum will buy. I snack from 3:00 to 6:00 pm, or from whn I get home to when I eat supper. Im quite active, but I do have my couch potato moments. ;) My cravings are beginning to give me mental fatigue, and if I don't eat consistently I just want to lay in my bed and sleep. What should I do? Is there something wrong with me?