I'm very sorry about your loss.
I am almost certain I O'd beofre my first AF showed up. But I didnt get pregnant. I'm 8 DPO now (first cycle) and I dont think this will be my cycle either.
I've also heard that women are very fertile after a birth or loss because of the extra hormones. I dont know if it is true or if the ones who have gotten pregnant was because of the hormones or because it was just their time.