AF almost 2 weeks late - PLEASE READ AND REPLY!!!

Hi guys - TTC#1 for 8 months now, my periods can be delayed when I'm stressed. Had an ultrasound and blood tests to rule out PCOS/initial problems and I was given the all clear. I was put on Fluoxetine last month for depression and anxiety and my period is 2 weeks late. I took a test 2 days before AF was due and on the day AF was due - both were negative but AF still hasn't showed up. Can Fluoxetine delay AF, could it be stress again or should I take another pregnancy test?