How to convince my mother for a second piercing?

Okay.. I know a gazillion people ask "How to convince my mom to let me get my ear pierced?". But for me, this is the most impossible thing ever. For a year, I've been trying to get either a midway piercing on my ear or a tragus piercing. Every time I ask her, she's just like "I don't wanna talk about it." or "No. I am your mother and I say no". Whenever I ask her for a legitimate reason, she never actually gives me one. I'm very confused. I'm turning 15 in a couple months and I feel I am mature enough and that I should have some say in what I do to my body. I'm a good child. I get okay grades, I don't do drugs or drink, I don't go out and party. I'm a very chill person. I'm not gonna ask anyone to tell me how to convince her, but just to make her consider it. Thank you so much!