Convince mother to let me get on the pill??

So I've really been wanting to get on the pill bc I'm sick of the guessing game that is my period and I do have a serious boyfriend. We haven't done it yet but I feel it happening soon so I want to be protected when it does happen BUT any/every time I bring up the idea of getting on the pill my mom spazzes out and gets squeamish and we don't talk about it until I bring it up again and the cycle continues. I don't want the pill just to have sex but she doesn't see it that way. How do I convince her to let me get on the pill?????? Any advice.