I totally get this, and my T has said something similar to me. It just takes time. My T didn't try to get me out of dissociation, and she allowed me to reveal my emotions as I was ready. In fact, she said that she really respects defense mechanisms and would never try to force her way past them, and I sort of followed her lead on that. It wasn't something I had control over. It was just at some point I was able to answer her question "How are you feeling about this?" with an emotion or experience rather than "I don't know".

Oh, and when they do start to thaw, it's hell for several months until you get the hang of it. Just letting you know now. But you do come out on the other side and it's not so bad after a while.