Is that sometimes facts can be interspersed with a negative picture of you that reflects a deep rooted antipathy/resentment towards you.
A picture that is removed from how things actually were. It can be as much about passing negative comment as it can be about providing
supporting details to help with your assessment. That's the situation with the letter my sister wrote.
Write your own.
If your memory is sketchy ask the family. You can write your interpretation of it.
I took a couple of days to write mine. I thought I had a bad memory. But if I closed my eyes somethings were either pin sharp or not.
My sisters and brother had a different family life. That's part of the autism story. "refrigerator parents."
Writing your own life history as supporting evidence is a really good idea
Yes,it's a good idea. However it's dependent on having a good recall of the past.My autobiographical memory is far from the best. I'm not very good at remembering specifics. It's very much the basic outline that's remembered.
Are you unable to remember specific instances from your childhood that would be suggestive of ASD?
I remember in a broad sense that my brother and sister were much closer to each other than I was to them. I don't recall engaging in much,if any, imaginative play with them. I had the usual toys boys had ,but had difficulty knowing what to do with them. I had no close friends . There was one boy I thought was a friend but on hindsight I think he was just someone who was a little more friendly to me than the other boys.. I was not good at engaging with other children. I was a little obsessive about collecting baseball cards when I was in America and football cards in the UK. I had difficulty seeing things from other people's point of view. If I said x it had to be x.
This is all really good to write up for your assessment though. I would say that it does show ASD traits too.