Plus I had the capacity to learn a lot more as a child than I actually did.

I feel like this is true of the majority of people. I, for one, know that when I was doing math in grade school I usually grasped the concept on the day it was introduced, yet was forced to repetitively solve quiz-like problems for weeks afterwards. This only served to make me absolutely hate the idea of math. And I don't believe my ability to understand the concepts was far beyond most of the others in my class. In my classes at least, the pace of instruction was always slowed to the level of the slowest students. I consider it a tragedy that most of my fellow students and I could've been hammering through calculus by eighth grade and instead were barely scratching the surface of algebra.