I Can't Lose Weight!

Hello, I am a girl of 14. I am 1, 70 tall and weigh 69 kg. I really want to lose weight because I have a belly and quite big thighs, but I just can't and can't. Both my mother and father are full and it must be genetic. In principle, at the moment my father is normal, but because he works a lot and has almost no time to eat, but otherwise he was full before and is prone to it. Last year I suffered hellish deprivations all summer, ran 10 laps in the stadium every day, ate a maximum of 700-800 calories and lost only one kilogram in 3 months, 2 cm from the waist and 1 from the thighs. Neither sport helps me, nor deprivation. I enrolled in basketball, athletics and dancing, I went to each of them for 2-3 months and stopped them because it had absolutely no effect, I did not lose weight, nor did my body tighten. For whole days I ate only fruits and vegetables and I constantly hoped to lose a kilo - it doesn't work! Now I don't play sports, I just walk my dog ​​twice a day, and the second time I walk 6-7 km. Of course, from this - zero effect :) I know it's up to the body, but still can you offer me a diet or sport with which to really lose weight? I can't take it anymore, I want to have a nice body!