What was your childhood like? I'm having VERY serious doubts about whether I am autistic

Hello everyone, sorry for the long post, I hope people will read or at least answer the first question:

I'm wondering what your childhood was like, how normal was it? Did you play with siblings/children? Did you engage in imaginative play?

My story:

For the previous 2.5 years I gradually became convinced that I must be autistic because I have a lot of autistic traits and score very highly on AQ50 and RAADS-R. Multiple people in my life have suggested to me I might be autistic which is what made me first research it. I'm at the extreme end for most autistic traits

So I pursued a diagnosis with Psychiatry UK, and am filling in this self-assessment form. Firstly it brought up a lot of negative memories. Writing about what's happened in my life (from teenage years onwards) is dredging up a lot of buried pain. But I'm also having serious doubts about the whole thing because of the childhood section. I'm so confused.

The thing is, I think I had a relatively normal childhood. From what I can tell I was a nice normal little boy. My mother says I was a normal baby and a "very good boy". I didn't cry too much and she never had any problems. I have teacher reports from primary school and my teachers all said I was settling in well at school, had an active imagination, and was conscientious and their favourite person to teach. I had swimming lessons, music lessons, I wrote imaginative stories and drew pictures of things I made up or invented. I did not have meltdowns.

I found a box of childhood photos and an old diary, and I appeared to do things with other people, I had a friend and went to his house, and mostly led a normal childhood. In photos I looked happy.

None of this matches the picture I had of myself as this autistic person who has struggled with everything. Autistic people should exhibit signs in childhood, they should not have friends or do normal childhood activities. Now I'm doubting it all, I feel like such a fraud. I was thinking of not even continuing with the assessment, but I suppose since I waited for so long I might as well go through with it - a negative result is still useful so I'll know for sure that I am or am not autistic.

But what I don't understand is how I have so many autistic traits. To name a few:

• I have extreme sensitivities to every sense which affects me continuously in every day life.
• I have extreme difficulties socialising, in responding appropriately to small talk, in connecting with others. I use stock phrases and learned behaviours that are what I think people expect of me, which is how I cope but it doesn't allow me to ever form a friendship and nobody ever knows the real me, I'm just pretending and it's exhausting.
• I continually misinterpret what other people mean, and they misunderstand me.
• I have no ability to read subtext or body language. I miss jokes because I don't realise it's a joke. I take things very literally.
• I don't use facial expressions and I talk in a monotone.
• I don't have much ability to empathise with others, and I don't understand my own emotions either. I basically have 2 feelings, good or bad.
• I have not been able to make friends at all for 20+ years, despite trying. I just don't seem to be able to understand other people.
• I struggle greatly with change and cannot cope with things happening unexpectedly.
• I do everything in a routine, eat the same meal on the same day, do everything at the same time and hate it if something prevents me from doing my routine. I can't do anything at short notice.
• I have very repetitive behaviour, I watch the same small number of TV shows over and over (hundreds of times), I will listen to the same song on repeat all day.
• I'm extremely logical and pattern matching and make connections where others do not.
• I have always collected and categorised things.
• I become obsessive about my interests and can't handle being interrupted. I will keep doing something or reading a topic until 6am every night and go without washing or food because I'm so obsessed with it. I have weirdly specific niche interests which I spend very long times on, obsessively.
• I stim every day (and I did used to do that as a child but got made fun of so learnt not to).

So what is going on here? When someone told me I might be autistic and I started reading up on it, it was such a revelation because it explained so much of how I am. It seemed to fit exactly, in every way.

So if I'm not autistic, then what is wrong with me? What happened to that sweet little boy I used to be? Autism is a childhood neurological disorder, you can't acquire it, so I don't understand why my childhood suggests so strongly that I am not autistic. Do I just have social anxiety and a lot of autistic traits? A variety of personality disorders? I can't explain the sensory problems though.

I keep vacillating between being certain I'm autistic and then thinking I'm a fraud and stupid to have thought it.