7 days late, negative BFN

Hey I am hoping for someone who can ease my mind- I am 7 days late, I’ve had dark brown discharge for 8 days and not much but maybe the size of a quarter every time I change my tampon. Maybe one tampon a day has a pea size amount of blood or less. I’ve taken test and got a BFN each time. Could that have been my period? I am normally regular with a day of brown discharge and then my period the next day for 6 days. This is very abnormal for me. Has anyone experienced this??

Also should mention that I had 18 days of high fertility last month with no peak.