late period a week

i was supposed to get my period a week ago. in the couple of weeks before that my boyfriend and I had sex to where he came in me 3 times. I am on birth control not trying to get pregnant. ...Now right now it is Friday night at midnight. on Thursday I took a test came back negative... still no period. is it more likely I'm just late given the fact I had a negative pregnancy test??? ..I know you girls aren t doctors don't get mad at me for posting a question.