My BB also does not know to turn over and not having any teeth. The nurse said it's also common especially in such a cold winter time that baby worn too many clothes. Hence they cannot turn so easily. I think we can wait for some more time.
I just took my son to his pediatrician for monthly regular check up, the pediatrician said no tooth yet is not a problem ah. Some old people even say better to have the first tooth later tim ... but I'm not sure why ah