Hey, well here's the thing.. The only way that she could get pregnant would be if she was ovulating(the monthly release of an egg).. Ovulation in most women occurs about halfway thru their cycle(about 2 weeks before her period is due), so if your girlfriend has a regular cycle, then she probably wasnt ovulating anyways.
If your both still nervous, have her take a home pregnancy test in 10-14 days..
Goodluck, hope I could help!
Oh ya, im michelle.. 15 yrs old and 12 weeks with my first child.... Im u ever need anything else pm me
or aim oangelcc543
:d