We often have to confront the undeniable fact that writing takes time away from other things that we, or other people, think we should be doing.
You have to pace yourself, like an athlete with an injury doing slow small exercises before returning to marathon running.
Work with your innate writing process rather than against it, and you'll be much happier and more productive.
Don't try to tell an "authentic" story. Instead, tell an "inauthentic" truth.
Critiques should not make you question the value of your work, or the value of yourself.
Let somebody else write only allistic characters. You can write a character who is probably, or maybe, on the spectrum, but this does not need a huge reveal or internal struggle—it can just be a thing you do, among other things you do, as an author.
The way you feel isn't a rational response to a defined situation, and can't be evaluated on that basis. Feelings don't stay contained and orderly. Some of your feelings may not even be about your writing.
Draw on the best of the way the world is and has been, as well as your most optimistic hopes for what it could be. The real world is very unfair to those on the margins. Use your writing to make up for it.
Today is the fifth Tuesday of the month, which means that my answer to this heartfelt letter is available exclusively to my Patreon patrons.
Let go of any inclination you have to identify with your work and interpret critiques of your work as critiques of you. Critiques of your work are critiques of your work. Your job is to use them to make your future work better.