BFN at 12DPO. No AF, due today, how long to wait after getting off BC?

This is my husband and my first month TTC. I have no pregnancy signs other than a couple days of nausea last weekend. AF is due today, but I tested on 10, 11 and 12DPO and all BFN. I got off my pill late June and AF started 7/1. How long did it take after BC (pill) for you to regulate? I have a feeling if AF is late it's just because I'm not regular yet, not because I'm pregnant.