I was diagnosed about 6 years ago.
As a child, I didn't have many friends. I always had one who I was very intense about that always ended after a couple of years. That is a pattern that has continued through my life until quite recently. I no longer have any close friends.
I didn't like to be hugged, I reacted to strong smells and sounds and I still do. I'm very photosensitive. I didn't behave as other children did amd spent a life time being asked why I couldn't "just be like everyone else?"
I didn't 'get' other children. I preferred to sit in my room and read than go out and play. I didn't do imaginative play.
As an adult I have a first class degree and masters but I'm unable to keep/stay in a full time permanent post. I need a 'get out' and full time is overwhelming - I try but it just becomes too much so I work in short term contract posts. I'm kind, friendly, loyal etc. But i struggle with friendships and relationships to the point where i no longer try.
I'd previously been heen diagnosed with depression and anxiety but I knew i wasnt depressed.
I don't get hints, don't like unsolicited touching, am sensitive to smells. I find NT people exhausting in their expectations of social behaviours.
I think I'm 'normal' and dread telling people in case inget the whole "you don't look autistic" but increasingly I'm finding that people have already guessed or know there is 'something'.
Life is hard work. People my own age sometimes feel very 'old' or at least very 'grown up' but people younger than me don't have the life experiences, but at least I don't feel stupid around them, so it's difficult connecting.
I feel most comfortable with people 10+ years older or younger than me because everyone expects you to be on a slightly different page to them so it doesn't feel odd.
Those are those things I can think of off the top of my head.
Most of my best friendships have been with other people who are on the spectrum or 'odd' in some way. We tend to gravitate towards each other and are more forgiving of each other's quirks.
My NT friend describes it as my Special Sensor.
Having a diagnosis helps because I can use the language to describe myself. It's not really made any tangible difference to my life.