I think want to have the sex but I know I don't want to have the babies

I'm a virgin and my boyfriend is not. he never pressures me or anything, but it's been going on six months and if I'm not ready now I feel as if I'm getting there. he's fine with waiting, but I always say despite my readiness it ain't gonna happen until I am on BC, he says that's fine but a condom is enough (y'all can argue if you agree with him or not but that's not good enough for me, I need that double protection) BUT I have a very over protective mom so I don't think getting birth control will be easy. 
I'm 18 and my brother was a junior in college when she found out he wasn't a virgin, and he was together with his girlfriend for six years but when she learned this she started a huge argument with him and stopped talking to him for like two weeks after this. I tried to bring up birth control in a discussion about a friend where I was saying her mom made her get the kind that you get inserted in your arm for "just in case" kind of purposes and i tried to slide it in their that if I were to take it I would just take the pill because it helps with acne and She said that it hurt and my mom was like… disgusted. my friend is 17 and when I told my mom this she was just like "why would her mom think that's ok, she shouldn't be having sex." (which not that it matters but she's not) and though I'm older than my friend and I decided that I personally wanted to graduate high school first (I don't know why, I just felt like graduating and losing your virginity are both big things that happen to a person and I wanted one to come before the other for some reason) and went on to demand that you should wait until you're married. keep in mind my mom got pregnant with my brother when she was 17 so while it's a little hypocritical I know it's just because she wants us to do better than she did. but I know people are like "you're 18, just go get it yourself" I still live in her house. I have to tell her where I'm going, I can't just be like "oh I'm going to planned parenthood to see if I can get pills" and she also was very overprotective to sort of a fault, she handles all doctor and insurance things, so I couldn't just call my doctor and ask them about it wouldn't work out, I get to my doctor through my mom. even if I did go to planned parenthood I wouldn't know how to pay for birth control hills with insurance because my mom handles it and I don't have money to just pay for it on my own. so I honestly don't know what to do. I'm trying to think of other ways to bring it up and make it seem like an acne only kind of need, or do you think since I'm 18 my doctor will just recommend it anyway when I go for my next physical? would like advice on the best way to bring it up without her going off on me