I would be gutted if a professional decided that I do not belong here though
If you feel like you belong, you do.
Doctors aren't perfect, they make mistakes. After all, every other doctor that you've seen in your 40 odd years didn't recognise your autism either, so while having an official diagnosis is great and validating, don't be discouraged or feel dejected if one more doctor gets it wrong. I believe we know ourselves best, and if you feel like autism explains all of your struggles (I know it did mine when I had my lightbulb moment in my 30's), then I'd go with that over what a doctor, however specialised has to say (I've seen neurodevelopmental specialists who sincerely thought adults can't be autistic, and didn't know about masking and other coping mechanisms we use to survive, so seriously, you can take their "expertise" with a grain of salt).
Good luck either way.