I totally get what you're saying Nick. I was attending a support group at the brain care centre, but I just didn't fit because I too seem to be the only one with overstimulation issues and the whole PCS thing. I felt like the odd one out too. Wearing sunglasses and closing my eyes.
Like you, I too felt appreciative of my injury severity as most folks had either severe brain injuries or strokes. On one hand I really admired their strength to overcome many physical limitations (many have walkers, wheel chairs, etc), but on the other hand at least their injuries were evident to people. I find expectations of me (family and friends) are often too high. But if you could see the suffering..... But in the end I am truly thankful to be as well as I am, it really can be worse. I plan to start back this Friday and was told that there is another person attending who has pcs. Wouldn't it be great to connect with a fellow PCS'er in person?!
Good luck with this program, I hope it helps you in some way. Even if it's just to help you understand your situation better and get the understanding from the docs that you need.