T.S.
It sounds like your daughter is afraid of the changes...What i would suggest especially that shes haveing dreams of being left behind is involve her in the packing. I know what can a three year old do? Have her help pack the linins, sheets towels , her toys things she cant get hurt on or break....also have you really talked to her about the move? Are you moving to a house? Do you have pics of the new place you'll be staying? Maybe giving your little one reassurance with out words is what is needed....do you understand? Showing her where her new home is maybe helpful for her to ease some of the fear she has.