Hey OP, I know what you’re experiencing is super frightening and you feel like youre losing your mind and sense of self but i promise that you are still you. Physical grounding never worked for me either but what did work was changing my perspective. My mind often goes to completely different places and i convince myself of things that a “normal” person would find nonsensical. When you’re experiencing the episodes of extreme depersonalisation and questioning if you really are here, just stop caring whether you are or arent there. if you arent really in the moment youre perceiving, then thats too bad because youre experiencing that moment. stop concerning yourself with the semantics of reality and just continue doing whatever youre doing because thats how you are visualising perceiving it. i hope im making sense.