I am pretty sure I know when we conceived and it was only 2 1/2 weeks ago. Is it possible to know that quickly? I spoke to my friend who is an OB and she is counting back to the first day of my last period which makes me 1 month along, according to her, which means my due date would be 2 weeks earlier than it is. Anyone know how common this is? Is this why a lot of babies are later than their due date?