I'm not sure of the answer, I'm pretty much the same. I can feel really awful say before a session, but it's like when I get in there something in me switches and I can just say whatever I have to say without any feelings or emotions. Although for me I'm pretty much like this in general so I'm not surprised at how I am.
The worst thing I find is when I feel sad etc after a session and think why didn't I show the struggle whilst I was there, does she actually think I'm ok, I'm portraying ok but I don't feel it inside. Will she understand without the emotion, etc...
we have spoke a little about this and I think she sees beneath that though and I think just knows that's how I've always been.