oddball, I dunno how late it is, but check this out:
http://www.ppslr.org/Medical_services/Emertext.htm
if it's been less than 5 days since sex, you're still in the window for the morning after pill... something to keep in mind.
also, TALK to your gf. you can't make these decisions on your own, she's definately gonna want to have a say in something like this... her body and all, hmm?