Be patient. Accept where you are is where you are right now at this time.
Keep going, keep talking about the frustration and disappointment and your wish to be able to say more.

Sometimes we do thing "This isn't helping".

I was like you, many defenses and for a long time. I often left with a splittig headache, or a need to eat, or crying from frustration and disappointment. It is Exhausting holding things in, even if you don't know what you are holding in or how to not hold it in.
My therapist is so patient and it has gotten better. There was no way through it but through it. I still can struggle, but I no longer feel it is awful, or the end of the world (which is how I described it). I sometimes still say that "I can't even do therapy right!", or "I'm a therapy failure" when I'm having a session where I keep shutting down.

When I first started, I barely spoke for 9 months. Mostly I just cried. Then I decided that I was going to talk about something, even if it was about baking christmas cookies! And so I did

Hang in there and keep talking about whatever IS going on internally.