I had sex with this girl that I know 1 month ago....?

So yea..she says she doesn't remember anything but I do. We had sex like at 3:30am in a picnic table. She laid on on of the sides of the seat, I took a condom and tried to put it but I did it wrong and it broke. I threw it away, took another one and inserted it in my penis (this time without breaking or anything). We had quick sex of about 5-10 minutes and I didn't ejaculate or anything. Today she says that she think she's pregnant and has taken a home test about 3 times and says positive. I told her to go tomorrow to the doctor and so he can check her (and if she's pregnant to take a DNA test since this girl is kinda slutty but said before me, she had sex 6 months ago). I took all the precautions in safe sex, didn't ejaculate, she was on her period that day (my mistake :S), and when I was young the urologist told me I'm 50% fertile unless I do surgery which I haven't (maybe in the future). So all of this plus the fact that the girl is very sexually active indicates me that I'm not the father if the case is that she is really pregnant....Do you think she is really pregnant, want anything from me (she is from Brazil, and don't think she's a citizen...I'm Dominican but I'm a citizen of the USA), or is it psychological. EVEN if she was pregnant I would ask for the DNA to confirm I'm the father. I NEED ADVICE. What do you think?