I want to get on birth control...

I’m 15 years old and I have a boy friend who I’ve been dating for a year and four months. We all ways talk about doing “things” and he has condoms but I think we both still have that fear of something happening (getting pregnant). So I would feel much safer doing things on the pill. I also get awful periods that last for like a week and a half and are very painful. Me and my mom have talked about taking me to the doctors and seeing what we can do about it. She’s talked about the pill with me once and she said she was on it when she was in college cause she got really bad periods but it made her moody and she doesn’t want me having sexism pretty sure. I want to talk to her about getting on it but I don’t want to have that’s awkward conversation with her. Also I don’t really know how birth control works with periods and things like that. So if u guys could give me advice and help me out here that would be great!!!