Why do I bleed during/ after I have sex?

I'm 20 years old and have been having sex with my boyfriend for two years now and it seems almost every time after we have sex I bleed. After or during, I'm not sure. Most times it isn't very much bleeding, but sometimes it is a bit more. We do not have sex regularly all the time, but even when we do I still bleed. He is the only guy I have ever been with. He has been with two girls before me, always used a condom and has been checked since them. We do not always use a condom, but he has never ejaculated in me. He either pulls out or we stop and put one on before it happens. I am on birth control- yasmin to be exact- but I have been on it since I was 16 for my skin. I have had a pap test since I've started having sex, and nothing has come back. Also, sometimes after we have sex it stings a little when I pee. I wouldn't say we are that rough, but sometimes of course we are. I'm just wondering if he i too big for me or what? I'm a pretty petite girl 4'11 115 pounds. He's 5'8 170 pounds. I've only had sex with him so I'm unsure on what penis size is small or large. I would say he is about 7 inches fully erect- I think this is average? Sometimes it hurts when he goes in me and sometimes the friction of him thrusting hurts. However, it isn't because I'm to dry. I get turned on very easy and get very wet easily. So I am really unsure on what could be the cause of this and am just looking to get some advice about this. Thanks so much!