Stretch marks - look horrible

First of all I'm not saying they are bad things, or ugly or embarrassing they arnt but I am just turning 18 and the WHOLE of my inner thighs are covered in dark purple/black stretch marks...it's starting to spread to the back of them aswell And it looks horrible, and I'm self concious on them. They are natural and normal and I'm not slating them but personally I don't like how bad these are and for what reason? Never had them before untill now and I've not put weight on and if so would only be a few pounds, I don't get where they've come from ... to be so young and be wearing dresses, skirts, bikinis in summer and have these. I'm self concious... Even if I just got them to a light colour so they arnt as noticeable .. They are so dark😭 Pictures don't even show how dark they are