Help..

So I'm almost 16 and me and my boyfriend have talked about becoming sexually active, and I want to get birth control, but I don't know how to tell my mom. I can't tell her it's bc sex, bc then she won't let me go out on dates, go to his house or him come to mine. I'm pretty sure she won't let me date in general. So I'm afraid. But, I also want to be the most prepared if we start having sex, a condom and birth control is better than just a condom. How do I ask?