24Days Late

I had unprotected sex twice before my missed period. I haven't gotten my period at all this month. I've had cramping and dizziness but when I went to the clinic I got a negative for my pregnancy test. Of course I already suspected I would because the first time I was pregnant I got a bunch of negative pregnancy tests until I was three months. I haven't been under any kind of stress so I know my period isn't late because of stress. I'm not in any medication that would affect it either. 😩 is there any other reason besides pregnancy for my period to be 24 days late? I already suspect pregnancy but I won't be sure until another month or so