Should I be worried? Am I expecting a baby?

I track my girlfriends period there are 6 days when she is in heat and one when she is olvuating. I had unportected sex with her on her last day " after she ovulated" we didn't think anything of it. It's been three weeks now and her period is suppose to come soon, but I am scared she might be expecting. She has been eating alot of random food and has gained 10 pounds since last month. She has had no morning sickness and no tender breasts. I think we might just be paranoid because her cousin started joking with her saying she was pregnant. I don't know if this helps but the day after we had sex she was peeing with blood?