Too Early To Tell?

Amanda
So...I ovulated on CD 27, I'm now CD 36.  Glow told me AF was due on 3/20, which would have been 9 dpo.  Today is 10dpo and nothing yet.  I tested Saturday (8 dpo) and got a BFN.  Is glow predicting AF too early?  Or am I actually late?  Should I test again?  I don't wanna be disappointed!