Birth Control Situation

I cannot figure out what to do about getting on birth control. I'm 17 & have been sexually active with my boyfriend for like 8 months now. If my mom knew, she would NEVER let me see him again. I want to get on birth control because I would feel more comfortable on it & I know my bf will too. Also my mom is completely against birth control, I've asked multiple times to get on it & she refuses. What do I do??? I'm terrified she will find out somehow & if she did I would never hear the end of it. Help!!