Telling my mom

So I'm soon about to turn 19 and I've been dating my boyfriend for a year and a half. We have a healthy, long distance relationship. Now we've been having sex for a few months now, we both lost it to eachother. My mom wants me to tell her when I lose it but then again I don't feel comfortable. I lost my virginty when I was ready... But I feel that I can't tell my mom because she's not ready.. She's supportive and wants me to tell her so I can get birth control and go see a doctor but I feel weird about it. I feel this way because whenever sex is brought up about friends, she always says something like she should've kept her legs closed or just because they've been dating for two years doesn't mean they can have sex. It's like she's contradicts herself and it gives me mixed signals. What should I do?