So, when we actually ovulate is always a best guess. And as you know though, sperm lives for up to a week. However, you have to have a penis in your vagina to get pregnant. You didn't have that except with condom so unless the condom broke or wasn't used correctly, I would not worry about pregnancy. All other calculations are too complicated to ponder. Really. All you need to know is that you can get a positive pregnancy test 2.5 weeks after your last episode that you are worried about and if you haven't gotten your period and suspect pregnancy, take a test. But women are late for their periods all the time for a variety of reasons. These include stress, changes in routine, losing or gaining weight, illness or just a hormonal blip on the radar. good luck