😔 I'm only 15 and my stretch marks....

My doctor says Im a little under average weight for my height and age. My boobs went from a C to a DD since December 2015 it's unbelievable. I didn't even know they could grow that much that fast!! I know they changed to that for sure because I got fitted multiple times. What can I do about these stretch marks 😞 I'm only 15 and I don't really want stretch marks that young.