OB paperwork

So I went to the appointment to fill out the paperwork. I'm telling you, there was more to fill out than at any other doctor I've ever been to. THEN, after I filled in all the blanks, the nurse took me back to ask me the same questions that were on the forms that I already filled out and then some.

The nurse calculated that I am due December 15th, making me almost five weeks pregnant, which is not physically possible. Because I keep track of everything like a good little Catholic wife who practices NFP, I know when I conceived and it was only 3 weeks and 2 days ago. For simplicity's sake, I'll go by what they are going by. Here's where we are so far according to American Baby:

Slowly at first, then more rapidly, the fertilized egg divides. The ball of cells moves down the fallopian tube until it floats inside your uterus. About one week after conception, or three weeks after the start of your last period, the ball of cells nestles into the well-prepared uterine lining.