Birth Control

Maybe this isn't the right place to post this butttt I'm 16 and I want to go on bc. I'm sexually active but I'm not looking to get pregnant. And if I'm not trying to have a baby what's the point in having a period? I'd ask my mom but like many parents she doesn't support sex before marriage. I want to convince her to let me go on it but I don't want her to know that I'm having sex. Any ideas?