Does Stress Cause Delay In Periods?

hi me and my boyfriend were messing around last week and he didnt penetrate his penis inside of my vagina all the way..he only put in a little bit...the head of the penis wasnt even in all the way and he didnt have precum but im still scared...i went to the doctor today and the urine test was negative so was my home pregnancy test...could i be pregnant or is stress delaying my period?