Ladies i need some advice please.

I am trying to figure out whats going on with my body. I was due for AF to arrive 10/24 and she did not show and i am still waiting. My cycles are anywhere from 24-26 days and that's it. I have taken 4 hpt and they are all neg. Does anyone know what i should do or what could cause it? I have had mild cramping and mild lower back pain but thats about it. I also have not been on BC for over 3 years so i know its not that. Can anyone help or has anyone experienced something similar??