The only thing is Pbn once told me the days until af is irrelevant, it has to do with amount of hcg in your system, which increases by dpo, so days until af changes nothing.. I guess that's why some women will miss a period and still not have a positive test yet :/ my chart is telling me that if implantation was day of spotting, I should have approximately 20 hcg by tomorrow. But that does me no good if my tests only detect 50 lol.