Ummm help :(

my bf and i had sex 2 and a half weeks ago and he pulled out. but before he pulled out he took a deep stroke paused for a bit and immediately pulled out and came. i was nervous but didn't take plan b. now my period is 8 days late and i took a pregnancy test 2 days ago which came back negative. i'm kind of stressing, this has happened before but i wasn't 8 days late. pls help what should i do.