I can almost guarantee that she is not pregnant. Females who are on their period usually do not get pregnant even with intercourse (there may be that one in a million case however) because when a woman is on their period, their body is getting rid of the material needed to maintain a pregnancy for that month that is produced during ovulation such as the extra lining of the uterine wall. You should be just fine, but if you guys don't want to get pregnant, you should really think about birth control. Good luck to you!
Tara
Kind of scares you into wanting to use protection. Good luck to you both!
If your penis did not enter her vagina there is probably less than 1% chance she got pregnant, especially since she was on her period.
You should be fine, but if she is late take a HPT and find out. Really though, the likeliness of her getting pregnant like that is like one in a million.