Sex prep... Sorta

Hi so my boyfriend and I have been debating taking anal sex for us a little more seriously. I know it's weird for a teen girl to be talking about this but just give me a chance. We as a couple dont want to risk pregnancy and my mom will not put me on the pill for reasons I won't talk about. We also both like the feel around there but haven't gone deep or for too long anal. So I need some help and advice for prepping and just advice on how to do things but keep it discreet. Thanks!