Late period but negative test

unknown girl

I was supposed to get my period the first it’s the fourth currently and I still haven’t gotten it so I’m a few days late I took a pregnancy test Tuesday the day after I was supposed to have started I took it around 6 or so that night and it came back negative. No even light line obviously negative and I still haven’t gotten my period any suggestions or advice. I don’t know why I haven’t started I’m always on time and never this late. There is absolutely no sign of my period no cramps no discharge change nothing