5 days late/bfn/dark opk's

Christine
Oh boy what a cycle this has been... I got two super strong positives a week apart (cd14&cd21). I was pretty sure I ovulated on cd15 based on bbt. AF was due 5/13 and no signs of her. I have tested and got all bfns. Just decided to take this opk which I know is negative but the test line is a darker then I usually get around my AF time or after. My cm is milky and watery, feel extremely wet. Wondering if this has happened to anyone? My cycle is 28-29 days and like clockwork. Could I possibly not have ovulated? Side note: I started taking b6 this month not sure if that has anything to do with it. Help, help and help. Please and thank you!