Birth Control

Okay so I want to get on the pill because so have really bad cramps, and my period is super irregular and heavy. But I also just want to be safe just in case i was in the situation where something were to happen with this older guy i like. I’m a sophomore in high school. Should I ask my mom now or should i wait until i have my physical in a few months and talk to my doctor about it? Also if i were to ask my mom how should i do it?