Orgasm/ Comfort struggle

My boyfriend and I have recently become sexually active and it's a new experience for both of us as we were both virgins (he's 20 I'm 18) and I just have some questions. We fore-played a lot before we began having sex and I always found it pleasurable, but now it feels uncomfortable to have sex not emotionally but physically. It always feels like everything is over stretched and tense and I don't like it. I've tried relaxing and the idea of sex doesn't stress me out, I just want to make it more pleasurable for myself and my boyfriend. Lastly I want to start on birth control but I'm not entirely sure of the process. We use condoms but I had a scare when I thought one had broken. Any advice or suggestions are welcome!!!