OKay, i may not be a guy, but i'll tell you this... if you are so worried about her getting pregnant, than DON'T HAVE SEX! I gotta tell you the one sure fire protection against pregnancy and STD's is abstinence. I can also tell you that if you are this worried about all of this, than you are probably NOT ready to have sex.
I know this is a hard concept to grasp, but if you wait until marriage, than pregnancies-even unplanned ones- are okay! you will be in love with your wife more so than you ever would have been if you had sex before marriage, and, did you know that people who enter marriage as virgins have a 60% lower divorce rate than those who don't?
Stop worrying about what's going to happen to you guys right now, and start worrying about what could happen in the future-what could be ruined if you take your relationship to the next level. I can tell that your relationship with this girl is strong, and(trust me on this), if you make even ONE mistake, you could lose that. Having sex is just a BUNDLE of mistakes waiting to happen. If you love this girl, than protect her from that devistation-protect yourSELF from that devistation! You won't ever regret it i promise