Same here. It's a tough one to describe.
I get overwhelmed, and I feel lost. I can't focus. Feel floaty, sometimes dizzy. My therapist appears blurry. I lose concentration & can't think straight or find words.
Sometimes I'm completely go, and my therapist will be calling my name to bring me back. No idea where I go either - maybe we meet up with each other in some dissassociation land lol!
Sometimes my therapist will say 'you are starting to dissassociate' and then I can usually come back into the 'present'.
Pandora, have you spoken to your therapist about this? Usually it's best to rewind to a few minutes before you started as that will show you a trigger, then you can explore it (if you feel safe & want to). But if nothing else you spot a trigger.