Suggest Precautions That Needs To Be Taken After Having Unsafe Sex

I had sex with my friend on day six of her period. Her period lasts for seven days and is on a 28 day cycle. That night we got drunk and had unprotected sex and I ejaculated inside; we only had sex once that night and never again. It s been two weeks and I am worried if she gotten pregnant, though there hasn t been any signs. I ve been doing a lot of research on the possibilities of getting pregnant on the last few days of a Women s menstrual cycle; and I ve been getting it is possible but very unlikely, because since a women is on her period she does not produce or produces very little cervical mucus and without it the sperm dies in a couple of hours not even reaching the fallopian tubes (where if it does reach it, it can last three to five days). I am just wondering if I am correct or I am completely off and never go into a career of medicine. I want to one day have a child but I am 26 and not ready financially or mentally. I know that I should always use protection and I have learned that the hard way being constantly worried. Please help with any information. Thank you.