pregnant or if its way to early to tell?

On Saturday October 13th i had unprotected sex and my significant other ejaculated a little inside of me. i usually get my period on the 21st but this time i recieved it on the 23rd today (not to late) and it is usually regular. I over stressed it of course because i am in college and dont really have time for a baby but i would make it of course if i was pregnant. About a week and a half ago my breast start feeling more and more tender ( they are usully tender the week before my period) and i felt on and off nausea throughtout the day for a week or so and even now occasionally now that im on my period ( i rarely ever in life feel nausea). For the first day its a normal flow period. i understand you guys arent gods but if you can answer if i can be pregnant or if its way to early to tell it would be greatly appreciated. thank you very much.