Agree that with a typical cycle, right before your period is expected is not the time you would ovulate. Occasionally a cycle is really off and we have a longer one than normal with late ovulation. Small possibility of that but none the less, a possibility.
I doubt you are pregnant but you could take a pregnancy test now or in one week to see.
good luck
Highly unlikely to conceive just 3 days before your period, simply because ovulation has most likely already occurred. Did you have intercourse before the 14th or is that the only time you had intercourse? If you had sex before this date, then it's possible you're pregnant. You can take a pregnancy test at least 2 weeks after intercourse so you could test now but like I said I highly doubt that if you are pregnant, it's from having sex on the 14th.
Many other things can delay a period. If the test is negative and your period still doesn't show within the next few weeks then go see your doctor.