Depersonalisation & feelings of unreality
 

Sorry to hear you're struggling with this - it can definitely be such an unsettling sensation.

Mostly I'd say grounding techniques: things like telling yourself your full name, your age, what year it is, and that you're safe. Maybe keeping it on an index card to keep on you when you're out as well.

Or focusing on something and describing its texture, temperature, color.
A frozen orange is actually good for this (as weird as it sounds) because it will be very cold, so you can focus on that as well as describe it, and it has texture with the bumps on the peel/rind area, and the smell of orange is strong so you can focus on those three things. Learned that in a trauma/dissociation unit. It might be worth a try. And you can refreeze it once you're feeling more grounded.

Sorry if none of that was helpful - I know there are more grounding techniques but these are the ones that came to mind.

I think the Orange sounds like a great idea. I find holding something small and physical like a small rock can help too but the frozen Orange sounds better. I hope you find something that works

First and foremost, relaxation techniques so that you're in less of an anxious state. But also I find just accepting it can help, rather than fighting it. If you notice that you're detached from yourself, notice it and move on to your usual activities. Also, I know it is much easier said than done, but ED behaviours can make things much worse, so try and keep on top of that when you can.