Convince my mom to let me wear powder?

i want to get a clinque powder foundation to control my oily t zone (it gets worse in the summer!) but my mother won't let me bc of wat happened in 8th grade. i wore liquid foundation (from almay) for a school play and it broke me out. but now i know more about makeup and know that mineral powder works best on me. she knows i have no probz applyin it but she wont let me! i did drag her to the clinque stand once (i had to repurchase my cleanser and i cant drive yet) and she said no because she doesn't want me to break out again! im 15 btw. i can probably buy it myself next time i go to the mall with friends but the prob is...if i ever wear it ill get caught cuz she like practically scans my appearance before goin out. like she examines my clothes and my face up close before i head to school! so she has a good eye for these things cuz you can see the powder particles in the sunlight. so help?