Why am I at 266 lb.s?

Okay I'm 16; 6' 2"; I obviously don't have a high metabolism. I do Martial Arts, everyday b4 cl i do an hour of bag work (240 lb. base bag) I can knock over the bag with a reverse punch, suicide sprints, paced jogs, sit-ups with 10 pounds on chest, elevated push-ups, with lunges and squats. all that in a hour for the last 2 weeks. thats b4 i do cles meaning 10 katas (all full power) all the equivalent of 1(+) miles of jogging, sparring and grappling marine special forces; and teaching lower belt cles. Plus I'm on a low-carb diet with my sis because she's getting her stomach stapled; I'm not being as strict; just breakfast and dinner are low-carb. school lunches aren't exactly nutritional. I eat plenty of protein. I am losing no F-ing. this is the first time I've checked my weight and height in the past... i don't know 3 months. What The F-ing Hell?