Horrible stretch marks!?

I'm 15 and I have TERRIBLE stretch marks on my stomach and waist. I'm so self conscious about it, you have no idea. Like I love the beach, but I haven't swam in like 3 years because I'm that embarred of them. What can I do to make them fade faster? They used to be REALLY red, but it has gone down a little bit but you can still see it from far away. I've only used palmers cocoa er, but that did nothing. What else could I use? Does bio oil work? Would a doctor or dermatologist help me if I went to them?