Don't worry (too much) if your dr can't pick it up. It has varied w all of my preg. DD1 we heard it at 8 wks, DD2 was 10 wks, DD3 10 wks, and DD4 12 wks. Position of baby and placenta can make a diff on when you can pick it up. I know it can make you nervous though when they don't! Hang in there mama!
Holly, mommy to 6 ~ 4 on earth 2 in Heaven