Is it possible you could be pg? If it was a erally light flow maybe it wasn't after all but instead implantation.
I did think of that too... and although I suppose it's possible, I honestly doubt it. I never got OPK+, and I started testing on CD 9. The flow wasn't a spotting where i could get away with maybe only using a liner - I def needed a pad or tampon and it was bright red.
Despite the OPK-, we BD on CD 10 and CD 13 just for the heck of it.
I also want to try not getting my hopes up because I dont think this was the month...