I'm 14 fat and unfit with moobs.?

I was never fat but my dad passed and I used to lift weights and bike with him but over the years I have put on weight and got fat. I am 14 about 5ft 7' and I weigh in around 13 stone, Its not obvious I am that fat but my moobs are rather large. I have tried push ups but I can't do one :( I have keep below the knee flat to the ground and I am doing this daily and cutting down on sugary foods, I eat when I am hungry and 3 times a day. I walk home from school with friend which google says is a mile and some, I have no weights and I am to young to go to the gym I don't like swimming because of my weight. What else can I do to lose the weight I do have rather large thighs and I am a 32-34 waist. PLEASE HELP! :(