How do I?

How do I bring it up to my mom I want to get on the pill. I am 13. I don’t have sex or anything that would make me get pregnant. I want to get on it to make my period more regular. I have had it for 2 years and it is still not regular the only time it is regular is the summer witch is fine and yes periods suck but for me it would be better to just have it every month then going 4 months without it and having it show up at random times.