How do I convince my mom to let me cut my own hair?

My mom doesn't ever want to take me to cut my hair unless its every 6 months(she says that she doesn't have enough "time" but she can take herself out every month to go cut her hair and buy shoes for herself o_o). I subtly cut my hair because she doesn't allow me to do it myself, but I think I do a pretty decent job at cutting my hair. But I don't want to subtly cut it every 2 weeks, I just wanna trim it to the length I like. I am VERY sure that I'm doing a better job than my hairdresser(my hair dresser talks to her coworker while doing my hair and she often messes up on it and tries to cover it up -_-). But anyway to convince her.?