is this fat or skin and what can i do about it? *pic*?

You can do nothing. Your legs looks to skinny actually :/ also on the side of that photo was other photos and I remembered the one about the thigh gap and if both were you you lost to much weight between them. You are beautiful in your own way and don't need to lose weight. Majority of girls have that issue with there stomach that's why most lay down striaight or at a small angle, or stand straightup at a beach because of this. It's normal so please don't freak out (: you are beautiful keep that in mind when deciding what to do...julio-hernandez1@live.com if you want to talk to a male teenager...

Um 10 pounds from 150 is 140. It looks like fat.

It's just because you're sitting in that position! Probably a tiny bit of healthy fat. You look great though and well done for losing the weight.

That's just you. Every skinny girl has that when they sit in that position