What Causes Delayed Periods With Negative UPT?

I messed up my bc for 2months really bad (had a period every 2weeks). I stopped taking it to give my body a break. My husband and I aren t trying but not preventing either... I m now 6 days late (I think, compared to my last period). I have had cramping but no period and brown smelly discharge. I took a test 3days ago and it was negative... Not sure if im pregnant or if my body is still adjusting?.. Can someone help???