This may be a long shot, but has anyone discovered types of meds or therapies that helped them with dissociation/depersonalisation/derealisation? I figure if there's anything in particular I can point a psych to as having good experiences/a good track record/etc, that will probably help avoid 'here are some SSRIs! now go away please!' (my brain doesn't respond well to basically any antidepressants but that doesn't stop the NHS prescribing them for everything)
