Im 13 years old and am not happy.?

I'm 13 years old and 5"5 tall and 12.6 stones. Is that healthy? I eat healthily and have no skin problems at all. I eat vegetables and fruits and hardly ever eat sweets unless my friends bring them in. I don't do a lot of exercise, apart from two sessions of gym per week however I walk quite a bit per day (not to lose weight but just walk from a place to another) and I sometimes swim in the weekends (for fun). Normally in the morning I'd take bread with cheese or cereal and then in school I'd take a tuna puff or a pastry (x2) during snack and a hot meal (e.g. lamb stew with mashed potatoes and salad) with a iced chocolate drink during lunch. When I get back home I have a quick snack (e.g. a grilled cheese sandwich with an orange/granola bar with tea) and do my homework then have dinner. During dinner, we never get our own plate, instead, my mom puts a plate in the middle and we help ourselves. We normally have a meat dish, and then rice or pasta and salad. I also tend to have a muesli bar or some crisps here and there. When I'm feeling really peckish, I normally have a nutella sandwich :) I leave home at around 6.45 am and come back at 4.00 and I have two hours of homework every day. By the time I'm finished with my homework, I normally have dinner, read and sleep. In the weekends I normally go shopping with my mum or hang out with my friends. Please help me. How can I lose weight? Please don't be rude and say "you're going to die by the time you're 22" or say "ewwwww". Thanks :) Btw, I'm not depressed or have an eating disorder. However when me and my friends fight, I tend to eat a bit more and we hardly fight :/ thanks :)