A.M.
first of all, there are MANY negative aspects to the cry it out method. there are actually 2 ways of thinking on it as well. the ferber tech where you keep going back in on specific times to reassure the child gradually increasing. then there is the 2nd approach which i see as people just letting their baby cry and cry while saying how dr ferber says its ok. although i agree with neither, i def see how people have twisted a dr's recommendations.
anyway, the cry it out idea is to have a child learn to self soothe. from your post, it seems that your child already knew how to soothe herself so she doesnt need to be "taught". to let her cry seems quite cruel. since she used to sleep ok, she is obviously tramatized by the current situation. children are very attached to their homes, and 18 month olds have a lot of separation anxiety. she is too young to comprehend this move, and doesnt know where her house is. she is probaly hearing, seeing, smelling all new things and is scared.
i cant understand how in your case you wouldnt cosleep to comfort her. you both would sleep better and you would be reinforcing her trust showing you will be there and not disappear like your old home. im not going to lie, i will disagree with anyone who says crying it out is a good thing, but in your case especially, i think its quite selfish and cruel. you need to put yourself in her shoes at just 18 months old. she is still a baby and is confused. im sure there will be issues in your new home as well, but thats just something we have to be patient with since we are the ones to put our children in these situations.
we moved into a horrible, little summer rental for 6 weeks as we needed somewhere to stay while our home was being built. for my husband and i, it was an awful experience. it was in a vacation area where young people had party houses and on the main strip where people were constantly walking by loudly. there was nowhere really for my 2 yr old daughter to play and all her stuff was in storage. we all slept together and she did fine. no problems at all. when she woke in the middle of the night from the people, she would just sit up, look at us and go back to sleep. no problems. if ever a child should have been upset about her living conditions changing, it should have been then, but she knew as long as mommy and daddy were there, everything was alright.
good luck