Sex before period and around ovulation.

It's been almost a year that me and my husband tried to conceived and that was after my 2 year old. We had sex the day before my period, my period actually came a couple days early but it was a regular 5 day period. We also had sex around ovulation withought planning or thinking about it. If I am being given a due date from my LMP and the ultrasound matched did I get pregnant a day before my period or around ovulation? Thoughts???