Alright. But I still prefer biology for myself.
When I told my OB/GYN I conceived on day 53 and I had the TTC chart and OPKs to prove it, they didn't know what the heck to do with me.
I told DH I should have just lied and made my "last period" be whatever 28 days it would have been than be biologically honest. LOL. Irregular women throw the whole thing off and it's best just to go by O day instead.