Missed period and negative test
I had been on birth control for over 8 years and came off of it in August. I have had 4 periods since with about 26 day cycles. My last period was on 11/24/13. I began going to the gym again a few days after Thanksgiving 5-6 days a week for about an hour of cardio and some light weight lifting, My period was due on 12/20/13, making me now a week late. I have taken 3 tests (digital and regular) and all have come back negative. Is there a chance I am getting a false negative or could my period just be late because of exercise and or coming off birth control?