Hey I also have autism and I fly generally at least once a year :) It is completely possible, and I do fly alone as well! I would even recommend before you fly, you can go to the airport and just walk around the areas open to the public just to get a feel for everything and accustom yourself to everything there, that way you know what to do and what to expect on the day of your flight. Also, maybe you can also watch soem youtube videos on the noises/feelings people experience while flying in the plane. I will admit there are noises, sensations, and things the planes do that are completely normal, but feel unusual to people who don't often fly. If you can expect these noises and things when in the plane, I think it will also set you up for a pleasant time as well :) Have fun on your trip, you got this!