I knew I was different, and so did people around me from an early age. I got behind in school and was taken to a private tutor who, unbeknown to me, told my parents the thought I was autistic, and then gave some reasons, one of which was how I held my pencil (?), but this was the early 80s, so the doctor didn't think I had it because I could speak and apparently looked at him in the eye when he was asking me questions. Well, yes, I was about 12 years old and knew to look at people when they are talking to me. He should have tried that when I was 5 or 6.
I noticed that I couldn't join in group social conversations in high school, just used to sit there not saying anything. Not processing fast enough. At the time I couldn't understand how other people were naturally able to do this, but I couldn't. Now I know.
In my late 20s/early 30s my social skills and emotional maturity caught up somewhat, but the social group slow processing never went away.
As a child, I didn't have issues with lights but I always had problems with loud noises, I have certain foods and textures I can't tolerate - before I knew about the autism I was cutting labels out of clothes and chose clothes for comfort rather than style. Now these modern white LED or energy-saving light bulbs really bother me.
So some aspects can really improve, or one finds ways of managing them, but others don't ever change.