I deal with this, though it was much worse when I was younger. I dissociated a lot and often felt trapped in my head in therapy, unable to express much, and unable to match my words to my affect. That was because I was heavily defended, maybe you are too. It was even worse when I had a not-good-enough therapist who interpreted my fear-based defenses negatively and couldn't help me with them. Sounds like hopefully your current T is good enough, so if you do trust him and want to connect more in session, I can tell you a few things that have worked well for me.

1. I talk about very focused, manageable topics first, so I don't get overhwelmed by a topic which makes it too easy to distance myself emotionally. I call them bite-sized.

2. I play music that helps bridge my internal, sometimes subconscious mood with my external expression, music that helps tell part of my story so I don't have to do the work of talking and feeling at the same time, or music that evokes an emotion so I can sit with that feeling.

3. I use anti-anxiety exercises in session to calm down enough to get back in touch with my underlying feelings. They help me feel more grounded which can help reconnect me with my emotions.

4. I am GENTLE. I don't push away my defenses or force myself to cry or talk or anything. I tried so hard to push through my resistance when I was younger, and I found by dishonoring my defenses that way, by trying to break them instead of respect them and help myself feel safer instead of forcing myself to discredit my feelings of being unsafe, that I made a great deal more progress.