Descretely get birth control?

I'm a young teenager that's sexually active, my mother is catholic and super aginst it and she believes I am a virgin. Me and my s/o use a condom so there's no STI's or pregnancy but I want to make sure I'm 100% safe. I told my mom my periods were bad and I wanted a type of birth control but she is aginst it because she believes birth control gave her the cancer. How do I get my hands on birth control without her knowing. I know it's bad to lie but I'd rather be safe. Thanks!!!