Stretch Marks

I'm starting to get stretch marks, no surprise there. I have stretch marks all over from puberty, 5'7" at 13 will do that to a girl.
What does surprise me about stretch marks is that I didn't need to run out of skin before they showed up. What the hell does that mean you ask? Allow me to explain, I still have fat hips with extra skin, I still have a fat roll in my back with extra skin. Why is my stomach not pulling from these "resources" before deciding that it needs to stretch my stomach?
I have been fortunate to locate a stretch mark lotion, no I do not believe it will keep these feinds at bay, but it does stop the belly from itching and that's good enough for me.