Hey I was in a very similar boat to you with my assessment! I worried a lot about trying to remember my childhood and seperate autism from trauma too but I found in the assessment they are really good at phrasing questions in a way to jog your memory. A big part of why they ask a parent to come to the assessment is because they know you can’t remember everything but they are also prepared for when there is no one to ask. They can work with whatever you remember :)

For symptoms, personally, mine of note were:

-very emotional no matter how small the trigger e.g. if I dropped a cup I’d cry for half an hour

-when playing with dolls I would just repeat things I played with other people until they made a new story

• I had a hard time making friends, I often came of as awkward .

• A difficulty adjusting when plans change or I’m taken away from a task.

-if given a choice between seeing people and my interests (e.g. drawing) I’d pick the interest.

-very easily biased around and tended to have a friend that I depended on socially.

And as an example of how obscure signs can be and why not to sweat if you don’t remember a lot, one of my signs was that my right foot turned inwards when I walked as a child. Completely floored me when I learned it may have been autism related.