How can my boyfriend and I gain trust from my parents?

I am a girl and I have been with my boyfriend for about three months now. We are both 16. A rule is that a parent must be home if he is over at my house or vice versa -- which I think is completely reasonable. However, my mom seems to not trust me at all, assuming that even with a parent home, my boyfriend and I will get into some sexual things (which, of course is possible for teens to do without getting caught but still). I just wish she would relax and realize that we aren't going to do anything bad. When we hang out we usually just watch a movie or play video games and cuddle. I do know for a fact that my mother lost her virginity at a young age and I guess fears that I will do the same -- but I just wish she would stop assuming that I do the same things she did. I do have an older sister who dated while she was in high school too, but I'm pretty sure my mother trusted her more so than she trusts me. Plus, I have done nothing to even lose her trust in the first place -- she has no reason not to trust me! Should I talk to her about it? I feel as though she'd just yell at me. Or should I just wait it out and see if anything changes? She seems to act very suspicious of my actions with my boyfriend and I don't understand why. It's almost as if she gets mad at me for doing something that hasn't even happened yet.

Thanks, sorry this was long!