How to ask my mom if I can wear makeup?

I'd just go up and talk to her about it. I'm sure she'll understand. She probably just stopped asking since she assumed আপনি didn't want to wear it at all.
Since you're in seventh grade (I'm assuming) আপনি can wear a little bit of makeup. I wouldn't go full out, but a little bit of eyeshadow and mascara and lip gloss is probably just fine.

What I don't get is why আপনি told her that 7th graders thought that wearing makeup is weird. I'm in 9th grade and the 7th graders at my school wear আরো makeup than I do. But, that's fine I guess.

Don't be afraid to ask her. If she's fine with আপনি wearing makeup, just tell her that আপনি want to wear it again. I'm sure she'll understand. :)

If আপনি want to be discreet about it (which I don't understand why, it's completely fine to be অগ্রবর্তী about this, especially if she's alright with আপনি wearing makeup) then পরবর্তি time you're at the store with her অথবা something, wander over to the makeup isle and look at some of the makeup there. Pick up some eyeshadow অথবা lip gloss and say "this is really pretty.. don't আপনি think? Do আপনি think it will look good on me?" And she'll probably suggest different রঙ to you.

Good luck. :)