You've gotten quite a bit of great feedback here. I can relate and have dissociated during sessions...even in group T, to a lesser extent.

One time, my T actually had to take me out in the rain in order to get me grounded. I, too, feel a lot of shame surrounding it, but T tells me that it is very common and very normal - and that it's a process to learn how to get grounded. He encourages me to work on paying attention to my other senses - feeling my feet on the ground, looking around the room and focusing on where I am, using my sense of smell or touch or hearing to know what's going on. It's difficult when you're in the midst of it, so it truly is something that needs to be practiced. Making T aware of it is the first step in working towards doing something about it.

Good luck!