I'm glad to read you've found some help and that you've found your non-productive hobbies again! The key in my opinion is to learn self-compassion and to expand your window of tolerance. When you're in a curious, open mindset, things don't feel overwhelming. It takes practice to get there, so be kind to yourself. But it does pay off to get out there and practice actively looking and listening without forming opinions or reacting otherwise. Maybe first just in small doses. In your case some bodywork might also be helpful: https://www.youtube.com/watch?v=oLBfCzvYS2I

Meditation is a must, I'd say. To cope with the constant sensory stimulation one needs to stay connected to one's internal signs and impulses. It also helps to learn to observe things without further analysis or reaction. I'd recommend looking into stoicism. I paint, write music and do all sorts of creative things, which clearly go hand in hand with an elevated sense of sensitivity. I definitely see it as a gift rather than a disability at this point in my life.