Birth control help

Well I want to be on birth control ( I'm 14 btw) and I think I'll feel safer and I don't have to worry about having a baby but I talked to my mom and she's not on board so I need some things to convince her. I asked her the other day when was her first time and she said she didn't feel comfortable telling me and she told me it was younger than 14 so I don't know what to do because I don't want to be a teen mom in high school because I have goals and I want to go to college and I know a baby would make it difficult. I even talked to my doctor when I went to get on antidepressants and she asked if I was sexually active and I said no and she said whenever I think I'm going to have sex to talk to her and she's put me on the pill because she don't want me having a baby when I'm not ready and she said she'd just tell my mom that I'm on the pill for my periods. But I need some advice on what to do.