Hello Lilfae: I see this is your first post here on PC. So... welcome to PsychCentral!

I hope you find PC to be of benefit.
I'm sorry but, like your therapist & others you have asked about this, I don't know what the experience you describe is either.

You asked if this is dissociation. It doesn't sound anything like what I understand dissociation to be. But then I'm certainly no expert on that subject either.

However here are 2 articles, from Psych Central's archives, one that provides a definition of dissociation & the other that attempts to describe what each type of dissociation feels like:
https://psychcentral.com/encyclopedia/dissociation/
https://blogs.psychcentral.com/couns...bed-in-a-poem/
The one experience I can share that is perhaps at least slightly similar to what you've experienced is that many years ago, when I would be in bed, I would feel as though my "consciousness" was floating up around the top of my head, if that makes any sense.

Way back then, I was into occult sorts of stuff. (That stuff was popular when I was young.) And I thought what I was experiencing was my "soul" trying to leave my body... sort of an astral travel sort of thing. And it always galled me that I could never actually leave my body.

Of course, nowadays I realize what I was experiencing was simply the effects of the high levels of unrelenting anxiety I lived with day-in & day-out.

Perhaps what you're experiencing is something similar?
The other thing I have come across in the past is with regard to feeling very big or very small. I've had this type of experience as well. For some reason I would suddenly have the experience of feeling very big or very tall, or conversely of feeling very small. I never knew why this happened. But I recall reading somewhere, quite a few years ago now, that this is an experience many people have & that there's no known explanation for why it occurs . It's simply one of those oddities of the way the human brain works. So I suppose what you experience could be something such as that too?
There is a forum, here on PC, dedicated to sleep & dream interpretation issues. That might be another place to post about what you've experienced. Here's a link:
https://forums.psychcentral.com/slee...nterpretation/
My best wishes to you...