birth control help!

so I'm 15 and sexually active , and not on birth control. my mom wont let my boyfriend come over because she's scared I'm gonna get pregnant. She said he can when I'm 16 maybe , still kinda debating since he's gonna be 18 . anyways , I said "just put me on birth control if that will make you feel better " and she was like "no just don't have sex yet" , i said "thats not all its good for" (since it helps with periods also) like I want birth control but don't want her to know I'm sexually active . HELPP! 😣