It's the overall picture that determines a diagnosis. Various isolated traits aren't very specific to any disorder because there's a lot of overlap - there's not enough here to go on. Once a clinician has enough of the pieces that fit a diagnosis they make one. Most people don't meet all criteria and don't have to. The diagnostic line varies between instruments and clinicians, confusing matters.
I remember sometimes walking around the playground at school by myself, twitching my hand. I remember teachers looking at me funny because of it. Also the teachers used to wanted to send me to a speech therapist. I hated loud noise (still do).
That could be stimming - one of the autism criteria. In high functioning people it's claimed they mostly outgrow it or never had it. It's not exclusive to autism though. Similar with the speech issues and noise sensitivity.
And then there was the obsessions; I used to scrub my hands with soap until the skin bled. I used to imagine there was some kind of slime on me that I had to keep scraping off. I had to keep opening and shutting the car door to make sure I hadn't trapped the cat's tail or something.
Most of the physical obsessions and rituals have now gone, but now I have mental ones. As I said in another post, I am obsessed by peoples ages, and I have to keep thinking about ages and dates of birth whenever I watch a film for instance. I can't feel any kind of mental calm until I've finished thinking about it. I get odd thoughts about my bones breaking that sometimes I struggle to get rid of. I have to do some kind of weird prayer thing before I climb into bed, even though I'm not religious.
Those look like OCD type obsessions and rituals more than autism ones. Autism and OCD overlap and are often comorbid.
Autism obsessions usually revolve around a special interest. The more circumscribed and unusual, the more it appears consistent with autism.
It's best to look at the core autism criterion which is the deficit in social and emotional reciprocity. It's a complicated matter though. As it's a spectrum it'll vary much between people with the same diagnosis and manifest differently in higher functioning individuals.
You can also not meet the diagnosis but be far enough along the spectrum it causes you problems that should be taken into account.