My breast are very sore 6 days after my period had unprotected sex my fianc he did orgasm inside me .1 day after my period. could i be pregnant?

Yes: It's unlikely that you would get pregnant on day #2 of your menstrual cycle. I like to tell my patients that there are no such things as a 'safe' day. 6 days after your period would be way early to have pregnancy symptoms as the pregnancy doesn't implant until 6 days after intercourse. I would be the soreness is due to something else. Take a home pregnancy test 5 days before next period due.