Pregnant?? Help

Charity

Me and my boyfriend had sex like 4 times within the first two weeks of January and he nutted in me all 5 times and 1 time the weekend I got off my period ( period was the 14-19) & we had sex the 21st and I took a pregnancy test today that was negative but I should be on my period this week like yesterday morning and I’m not and I have been having brown discharge but only within the last week but we had sex 3 weeks ago