Is it true that once you have cellulite it's permanent? Please help.?

I am a 13 year old girl and I just realized that I have a bit of cellulite on the back of my thighs. It's not much but I know that at 13 you shouldn't have ANY and it's really embarrassing. I will admit I'm a bit flabby but not necessarily fat. I am 5'1 and 110 pounds. I think I used to be fat I was like 5'0 and 120-122 lbs. could me being flabby with not a lot of muscle have something to do with it? Can my old weight have something to do with it? Please help, what should I eat and what excercises should I do to get it to go away. I've heard that it's permanent :(