Could I be Pregnant?

So I had unprotected sex on the 19th of this month and my partner wasn't sure if he ejaculated or not. I was due for my period 3 days ago and it still hasn't come. Usually 1 and a half weeks before my period I get really  sore boobs but I didn't this time and now I have slight tender breasts on the outside of my boobs but no swelling. My cycle is usually 30 days and my last period was on the 29th of July - 2nd of August. I've had some dizziness aswell. Could it be that I'm pregnant?