This link will give you some excellent advice.
http://www.yorkietalk.com/forums/gen...nt-advice.html
My Brandi was rescued from a byb. While the conditions she came from were pretty bad, it wasn't as bad as the environment you have described. I used some of the advice from this link to help with Brandi.,....and boy did they worked.
I watched a submissive, skittish yorkie who was afraid of everything blossom into a full blown diva who now thinks she can boss the cat around.
Good luck with your little one