TMI no pic AF on way?

LJ • Baby girl born Feb 19, 2015 and second girl born Jan 20, 2017. Hoping to convince my husband to try for a third!
CD 26 with AF due on the 28th.  Figure about 12 DPO. Did a pregnancy test today was BFN. When I checked my CP it was very high and firm but there was some light brown / pink mucus on tip of finger. Any thoughts onto whether this is just AF on her way?  Does anyone ever see blood that early?