It all depends on what "doctor" you're talking about. If you're talking about a physical doctor, I don't really think that's the way to go (but that's my opinion). General practitioners and physical specialists (such as ear, nose, and throat doctors) will not know much, if anything, about autism. The best you can do is talk to your psychologist about possibly being autistic, and then ask what psychiatrists they can recommend you to (if they cannot diagnose you themselves). Sometimes a therapist can't give you psych evaluations, however, mine did. They just weren't as thorough as a Child Development Clinic within the same area. You're looking for someone to either hear a lot about you (your behaviors, meltdowns, stims, and special interests) or spend a few hours with you and observe that behavior themselves.
I wish you well!
~SDR