Period late

Ashley

According to my eve tracker I was supost to get my period around the 13-19 of this month so I waited like I would usually do but after a week and a half nothing and the month is almost over and nothing still. My bf and I have been having sex without a condom for a couples of times before and i took a pregnancy test just in case to make sure and it came out negative. But i still have no period so I’m completely got no idea what to do. Can anyone help?