My girlfriend and I had sexual intercourse around day 17 of her cycle (which is very regular and usually lasts 28 days). She does not use hormonal contraception. I used a condom and, moreover, at the moment of ejaculation, I withdrew my penis from her vagina and ejaculated outside. After that, about a minute later, we continued kissing (she later stated that she felt my unprotected penis touch her vulva), and I put my fingers, possibly with some semen residue, inside her. I didn't clean my penis or hand during this time because we were in a car.
Currently, she is 5 days late, and since she always claims to have a regular cycle, we are very worried. What gives us hope for the delay is the fact that she contracted the flu between days around 10-15 of her cycle, and that she was very stressed at work during that month. I suggested she take a pregnancy test to reassure us/be aware, since it's been 2 weeks since we had sex, but she said that talking about it only makes her more anxious.
Any tips or advice?