Sex is a sin

So, I'm 18 years old and I wanna tell my parents that I want to be on birth control but my parents are extremely religious and believe that sex is a sin and I will go to hell for it. They don't know that I'm not a virgin and that I lost my virginity at a young age, I'm very sexually active and I think it's important for me to be on Birth control. I'm so nervous and and anxious on how to even bring it up. So any advice would be nice!