What Causes Delay In Periods And Excess Fatigue?

Hello,I had sex 2 weeks before my expected period, but he was only inside of me for a little bit until we put a condom on. Then we had sex again protected the day before my expected period. He never used a condom with his exes and they never got pregnant. My period is now 3 days late, and I have been feeling very tired and hungry. I have taken 4 pregnancy tests since my missed date, and all of them were negative. Did I just ovulate late and thus my period will be later? Thank you.