Preg test neg but still no period?

Steph

Hi, I was hoping someone could give me some insight. I had unprotected sex (past my fertile window if it matters) two and a half weeks ago and my period is now six days late.

I took a pregnancy test today and it came back negative. I’m not sure what else to do but I’m nervous about my period being late.

I recently got off birth control three months ago and I don’t know if that’s a possibility for why my cycle is irregular?