have you tried visualizing the session? idk. in dbt we call it coping ahead. like sit quietly and close your eyes. imagine the session. imagine yourself speaking in the session and imagine yourself actually doing what you want to do in terms of sharing and emotionally connecting. i do that sometimes. i still struggle to make the emotional connections sometimes, but i do find that i can at least avoid the shut down and at least articulate what i'm experiencing in being emotionally distant while adeptly speaking to the problem.
also. notecards. i'm thinking of taking a notecard to my next session