A pregnancy question?

It will have been 5 weeks since me and my gf had unprotected sex, we had sex on a wednesday, then the next day she forgot her birth control, then the day after that we had sex again. i finished inside her like 6 times. 5 weeks later (now) she has headaches all the time, really tired all the time even when she has slept alot, tender breasts, and nausea sometimes. is it possible she is pregnant? we are waiting to take a test