Help! Period is late

Alma
I am so confused. We have been TTC for a year in a half. My cycle is always like clock work 28 days always ovulate the same week. Well this month I did not get a positive ovulation test at all!! And then when my period was due I spotted for an hour. Like brownish. Then gone!!! 2 days later and still nothing!! I took the pregnancy test and negative!!! Any input Is so appreciated. I don't know why my body is playing tricks on me this month!!