Pretty good. That's about the time most women ovulate. Have you taken a test yet? If not, I would.
Very likely that you are pregnant. The only way to know is to take a test. You are also not just a little late but 3 weeks late so take a test ASAP to find your answer.
I think that it's likely that you're pregnant, especially because your period is late and you had unprotected sex around the time when you likely ovulated. You should take a home pregnancy test to make sure.