Need help with stretch marks plz?

im 14 and skinny with bigger than most girls my age. and i kno ALOT of girls get stretch marks and that theyll eventually go away. but the stretch marks on my are a darkkk purple and cover practically everywhere. i cant change in front of sumone or wear a swimsuit cuz of how bad it is. any help to get rid of them? lotion doesnt help much with me.