So, I want to say to totally take control of the environment and maximize it for happiness / soothing qualities. I use candles (supervised of course), scents, stuffed animals, favorites (toys, books, etc.), drawing space for nonverbal expression, music of all types (so powerful for every type of mood) and on and on. It might sound like a lot of work and attention to detail, but that is part of a lifetime of happiness for us. When I used to travel before all of the new air travel rules, I was the person scenting the air for fresh cotton linen scent if I was sitting next to a person who did not shower. We have to control our environments. The upside is to think of all of the great products we have because of humans with high sensitivities. I even buy my child luxury bath products if I can afford it (lavender is soothing). Chamomile tea (lots of teas) are soothing. When you visit the UK or even Seattle for that matter, you realize why humans have their routines with tea and coffee. I hate to say it but comfort food is an option but then the calories are always an issue. Anything that is a negative now could end up being a huge positive in adulthood. Remember all of these stages are temporary. A sensitive child could be the next huge designer, perfume inventor, artist and on and on. You are not alone. It is very difficult to parent a gifted / highly gifted child. It takes a lot of energy. It sounds like you are right on top of it. Great job! Hang in there.
