Help !!!

Me & my boyfriend were in the moment on December 29 & I let him stick the head of his penis in me without a condom & he went in & out 3-5 times . He was no where near cumming & never has any Precum . My period was supposed to come on January 8, and was a week late last month .  I have been having stress about this & a few other things & my period is 21 days late . I took a test when I was 1 week late , 01/17/2015 & it was negative . Don't really have any symptoms .  I Need some advice. Im going to take another test this weekend .