At one time autism was not known, until Leo Kanner described it. Just because the DSM has not caught up with the research that does not make it less real. I disagree that there are no criteria. Unfortunately there is no test like for strep throat and we have to rely on the reporting of parents and teachers.
One difficult question is "Where is the cut off point. We all have sensory peculiarities, but when does it become a disorder?"
So I have many strange behaviors but I've usually assumed it was my social anxiety until I came across something on the internet about Sensory Defensive
I'm a teen who was diagnosed with level 1 autism at age 13. Since I was very young I had sensory issues, they were very noticeable when I was in preschool,