My wife's second opinion meant she got her autism diagnosis because she previously got a different diagnosis. Meanwhile her sister got ADHD diagnosis but second opinion also autism diagnosis. Their brother is as obvious on the spectrum, having the more obvious classical traits (by the T).

Our diagnosis involved heteroanamnesis, and many, many questionnaires and interviews. By a team with each being a specialist in the field on a different facet.

I cannot recommend getting tested enough. Because those who suspect likely researched into it, and are being told traits get recognized or they're facing challenges in their life. But I live in a country with a sort of working social system which (although weakened) so mandatory insurance worked. If you do not have access to that I'd sing a different tune... and in such a society it is very likely a lot of undiagnosed and stuck people are runnin' around.