The first day of my last period was

Patient: The first day of my last period was Jan.8th which last 5 days. I had sex jan.17th,22nd, and 24th. when do you think the actual day of conception was? I got a positve pregnancy test feb.11th

Doctor: Hello,Thank you for your medical query at AskTheDoctor.comI understand your concern.Since the first day of your cycle was January 8th, your expected ovulation date would be any day between 22nd to 25th of January. It is difficult to exactly predict, but it is likely to be either 22nd or 24th. It should not be 17th as ovulation is not expected that early.Hope this was helpful,Regards