Dont know how to ask

So im in highschool (dont want to say what year causw probally gonna grt hate) but i have recently become sexually active. We use condoms, but we also go with out at times. I told him we need to stop doin that and we need to buy more. And he agreed. He has always pulled out even with condoms. But im still worried about getting pregnant and i really want to ise birth control to help and ti help settel my mind a bit. But my parents arent really that that strict but would murder me if they found out i was having sex. So idk how to get it or ask them........how do I ?!?!?