I feel for you. I tend to go numb/dissociate whenever I'm emotionally overwhelmed or frightened. On the outside everything seems normal. And it took us (therapist and me) quite a while to catch on to what is happening.

Basically, dissociating is your brain trying to protect you from emotional overload. It's some form of coping strategy that probably at some point in your life was life-saving for you. Problem is: it's not longer really helpful but hindering you from getting better. So it's time now to un-learn this coping strategy. Which takes time. After all, it took you a long time to 'learn' to dissociate that effectively. So it will take time and exercise to start re-building different strategies.

From what you write, it seems that your therapist gave you exercises that might be helpful. If they don't help, talk to your T about it, and start experimenting in adapting those exercises. This is not a one-size-fits-all approach. Strategies that one person might find helpful aren't helpful to the next person... And it's not a straight road. It takes trial and error, and trying again different things. So be patient with yourself and give yourself time. This time is definitely not wasted!

Wishing you all the best,
c_r