Hey man.

It's very unlikely that she's pregnant, though not impossible. I'm not entirely knowledgeable about women's menstruation, but I know my girlfriends period sometimes varies more widely than other women and it's unpredictable when her period will do this, just because she hasn't had it yet doesn't mean she won't have it. There's not much else you can do at this point other than wait until she can take a more accurate test (or she gets her period), but even if she is pregnant it's not the end of the world. There are plenty of options if you both decide you don't want the child.

Whatever the case is, take this as a learning experience. You've gotta be really careful in sexual encounters because if you do happen to get a girl pregnant you're stuck on the hook for 18 years of child support and you have NO SAY in whether she keeps it or not. As a man, you are at her mercy in terms of pregnancy.

Hope you get some good news, and maybe you should start discussing what options you two may want to pursue if she is pregnant (abortion, adoption, signing guardianship to a family member).

Good luck man, I know how scary this can be. Keep us updated.