Why do I feel weird about being intimate with my girlfriend?

So I've been with my girlfriend for about 9 months now. We were in an argument a couple days ago and she came over my house. We apologized for our behavior, tears were shed, hugs were given, etc. Anyway, she had sex that day. This was our argument:"About a week ago we got into a huge argument and she thought it was going to be over, I thought that too. In fact, I broke up with her for about 5 - 8 hours before coming to my senses and ran back. Anyway, she stopped taking birth control because: "I'm sorry T-T I couldn't let you leave me". We've had sex twice since that. Today is the 26th of June, 2011, she stopped on June 22. I was just informed today." I still love her.That was our argument. We had sex and we tried something new (without getting into detail) it felt good but I, myself didn't really feel connected. I felt like i was with a new person. Like a friend with benefits, like... i ts really, really hard to explain. We talked it over and we came up with a bunch of ideas why it felt like that. What do you guys think? Did we have sex too soon? Btw, when we were good, sex was really good. We felt connected, together, loved, it didn't feel new and "friendly"