I wasn't allowed to wear makeup in middle school either, as much as I hated it, your parents know best. My older middle school years I started to get acne, so I was allowed to wear foundation and some lip gloss. By my freshmen year I was only allowed foundation, lip gloss and eye shadow. I was reading all the other answers and allot of them are right on, instead of trying to hide something, why don't you sit down with your mom and tell her how not wearing makeup makes you feel, and maybe if she sees how mature your being you can strike up a compromise that both of you can agree on.
Here's a hint that might help ya win her over: My mom's reason for letting me wear makeup in middle school was this, "pretend a kid is a spring pinched between you fingers, what's gonna happen if you open your fingers fast? It will fly away! But what will happen if you open your fingers slowly? It will say in your hand. That's the same with wearing makeup, What's gonna happen if you deny someone something for a long time and then let them have it all at once? they will most likely over indulge, (you could ask her: "you don't want me to look like a clown do you?" lol) but if you give someone a privilege a little at a time, they are more likely to be able to handle the full responsibility! :) Hope that helps and makes sense lol!