advice on Spotting

Sooo my period is due to come on today.... Nothing yet... But 7 days before I was light spotting only when I wipe... Light pink and slimmy... I never had this happen and I always had a normal and regular period... No signs of my period is happening but I took test BPN... Sad now but it's always bn on time.... What's going on? I'm TTC baby #2. Not on birth control and been trying over 2 yrs. advice please???