Rescued puppy mill dog..?

In November of 2009, I adopted my Shiba Inu from Best Friends (Dogtown) in Kanab Utah. She was 8 almost 9 years old. She had lived her whole life minus 6 months, in the puppy mill. She was a breeding machine and if Best Friends would not have taken her when they did...she would have been killed and not in a humane way (she was unable to produce anymore puppies). I have no idea what she endured in this mill. I have had her over a year and she still acts like I am a stranger. I treat her like a queen. When I come home from work, she actually will great me at the door...with her flat ears and squinted eyes (she does this when she is happy), but then 1 min later, she goes back to completely avoiding us. She will not let us touch her stomach or backside. She only really pays attention to us, when she is hungry, needs to go outside, is scared by a noise, she is jealous that cat is getting attention or I have been gone for 8 hrs and she says hello. She will take one step forward and 5 steps back. I know she may never come out of this and I am happy the end of her life she will actually get to be a dog, instead someones source of income. However, I would like her to show us that she loves us, like we love her. My cat acts more like a dog and my dog acts like she is the cat. Anyone had any problems getting there puppy mill rescue dog to open up?