Hi, Welcome to Healthcaremagic.com. I had gone through your question I can understand your concern about your drug interactions and pregnancy issue. As per your history, you had asprin for the painful cramps related to periods. There is no known marked interactions between the two. But severe pain and strong painkillers can raise the blood sugar level in body thought one you had is safe. Because you had sex three days before your normal periods, that falls on safe period, so in my opion there is least chances or no chances of pregnancy. In case your periods are delayed more than a week or two, you need to get a home pregnancy test done. Hope my answer will help you and visit us back if you have any further queries. Regards Dr Muzaffer Hussain Parray.