Babies move around. Its normal. As for being small that is Just a guess. By multiple ultrasounds my daughter was measuring almost a month small and at 39 weeks was born at 1 oz short of 7 lbs. Bigger than my daughter who was measuring right on.
I'm confused about what happened. Is she still feeling movement? If you get the feeling that things are not okay, you should call the OB. I don't think that anyone other than her doctor should be trying to move or change the baby's position.