I think it's pretty typical for the emotional response to continue after therapy (the "therapy hangover"!). I know I tend to have more PTSD symptoms for two or three days after a session, sometimes more.

I also understand the frustration of the time it takes to reconnect with your T and your emotions once you are finally in session. One thing that helps me is taking some time the night before and also the hour or so before the session to look through my journal and see how the week was, what I was thinking about. I often create sort of a bulleted list of two or three issues I want to discuss. This helps me avoid the panicked empty mind.

I wonder if you could ask your T for longer session times, since you meet less frequently? That might take some of the pressure off enough so you feel more free to talk.

I encourage you to browse this Psychotherapy section and also the PTSD section, they helped me feel less alone in the process.