I was never pregnant that's why I'm curious
Without ovulation pregnancy can not occur as there would be nothing for the sperm to fertilize. I assume when you say ovulation test you mean online calculator, as a true OPK doesn't predict ovulation a week in advance. If this is the case, it's not exact and should not be relied on.
Sperm can survive for up to 5 days. If you ovulated on the 12th and you had sex 5 days before it is possible that you could be pregnant. However the baby wouldn't have even implanted yet so you wouldn't have any symptoms. Most symptoms don't occur until AFTER you get a positive pregnancy test.
It's not even January 20th yet... Do you have your dates mixed up?