AF late

Caila
I was due for AF a week ago. I have had very mild spotting today. Red when went to the bathroom in the middle of the night and now just random brown discharge. I took tests during this past week and all were BFN. I called the doc to talk to a nurse and she said if I were pregnant I would have seen a BFP by now. I experienced terrible cramping, nausea, and slightly tender breasts. Don't know what's going on. I know stress can delay period but this has just been different this time. My husband and I have been TTC for 6 months. Still trying to get to know my body off the pill so this is making it even more confusing. Anyone with a similar experience, or suggestions/advice? 
Thank you