Definitely give meditation a go jay,its literally the one thing that keeps me stable and moving forward in life.Stick with it for a while and it should help greatly,it can take a while for your brain to adapt to a meditative state.
One thing to be aware of though is that meditation can increase pineal gland activity and Im aware that your condition is relatively severe so I would encourage you to look into "grounding" techniques to accompany your meditation practice if you decide to start(in reality everyone should but especially those who are already sensitive in that regard).I'm not sure of your beliefs or perspective on the matter but a big factor with HPPD is what is eseentially an overtly expanded conciousness.Lots of people who have tried psychedelics or meditated have experienced this state of "oneness" with the universe but the issue with people like us is that we never fully came back,we are perpetually swimming in a sea of universal expanivesness with a lack of tether to reality or our bodies,thus the feelings of depersonalization,disconnection,anxiety,etc.Grounding is the practice of bringing that consciousness back into the physical plane of reality,just like how a electrical circuit needs a grounding channel otherwise it overloads and dosent have a proper conducting pathway,does that make sense?
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This stuff may seem really esoteric and conceptually it just sounds like a bunch of new age jargon but I am confident that if people investigate these avenues of healing they can have some pretty profound breakthroughs.Even fifteen years later I think you may just surprise yourself,take care man.