Help! Late period, brown discharge

So my bf and I have been TTC and I've been having regular periods for the last 7 months (I have PCOS so sometimes periods don't show up at all!)
I've been due on for nearly two weeks now, did a pregnancy test which came back negative. 
For the last 5 days I have had consistent brown discharge, only when wiping, with tacky/sticky darker pieces but still no period. 
Not sure if this is just my body taking its sweet ass time to bring AF or possible early pregnancy related issues/chemical miscarriage/ectopic pregnancy etc.
Anyone else experienced this?!