Janel, I have a ton from puberty as well. Mostly on my hips and boobs, but most of them were so old you couldn't see them.
Some part of me is really skeptical of anything to prevent stretch marks. I didn't get any stretch marks with my first until about 38 weeks or something like that, and then I woke up one morning and was suddenly covered in them. That made me decide I should never get my hopes up! With my second I weighed more than I ever had in my life and got zillions of them, a lot on my hips and thighs, etc.
But reducing already present stretch marks.... Yeah, that sounds good! And I'm itchy. I'm going to try it regardless of my inability to trust, haha.