For the first time in two years, I'm with a girl, but...

Well, its been almost two years since I have had sex, and now a new girl had just entered my life. But there are a few problems:

1. She is a bit younger than I am and a lot less mature, to a point I think I don't respect her as much because of it. (She is a party animal and I'm more of a home person)

2. She has a lot more experience with males than I do with female, to be honest I have only had sex with that one girl before, while she has a a number of boyfriends before. (We had sex last week, but then two days later I kept losing my erection just before intercourse due to performance anxiety and discomfort as I'm uncircumcised, it hurts when I use condom. I'm going to see the doctor tomorrow.)

3. In the beginning I tell myself that I'm just gonna hang out and have fun with this girl, because I sense she is really doing the same thing. In the first night that I was with her, I asked if she want something serious or just for fun, her reply was "I was always serious with the guys before...", later on she mentioned that she is "****ing with me" right now. I think I understand that this is better for me if it is just for fun, but for some reasons I just kept thinking about her.

4. I can't help but want to see her, talk to her. But at the same time I'm afraid I'm going to invest my emotion into this girl. Only to be hurt later on.

What do you guys think about this?