Am I underweight, healthy, overweight, obese, or morbidly obese?

I am 13 Yeats old, 5 feet 4 inches and 175 pounds. I think I'm fat. When I sit down, I have four rolls of fat :( I can't see my toes when I stand up, neither my belt or top of pants or much of the floor. My fat literally folds into itsself when I sit down and it's disgusting :( I also have a double chin (how do I get hat to go away?!!!) also, since I'm sure I'm fat, tips on how to lose weight? No supliments please. Diets and exercises only please :) in my favorite store (aeropostale) I am an xl and I've almost grown out of it. And in pants there I'm a vey high plus size. I eat a lot of junk food, soda, iced tea, and I hate exercising, no joke. Some people make fun of me at school, but my friends stick up for me. I have very low self-esteem because I think I'm overweight. My grandparents also ridicule me about my weight because they are very health-concious. So, what catagory do I fall in, how do I lose weight (no supliments!), how to get rid of my double chin, and how to be more confident?? Thanks people! :)