Psychiatrist or psychologist (the one with PhD) would diagnose ASD in adults. In my experience adults seeking ASD diagnosis do not need to see a neurologist.

Ask your doctor to refer you to a psychiatrist. Or it depends on your insurance make an appointment yourself or see if you can get access to clinical psychologist. If you could find one, then it would work too.

Asperger’s isn’t a valid diagnosis anymore. It’s weird doctor would tell you that in 2017. It hasn’t been a diagnosis then. It’s all Autism Spectrum Disorder. What was called Asperger is a mild ASD, that’s why it’s a spectrum.

Did that doctor formally diagnosed you or just suggested it? You could try to locate those records or go see those specialists I mentioned above