12 and fat

Hey guys........ I'm Morgan, and I'm 12 years old. I have a really bad problem with eating unhealthy food and I get bullied a lot for being overweight. My own siblings bully me because of it. I don't feel like Morgan when I eat like this. I tried going on a diet and it helped but i ended up gaining the weight back and more because I didn't have the right mind state about exercising. That's my biggest problem. " exercising". Anyone have any advice on this? If do pleeeease help