The reason people go to professionals is to get *their* professional opinion, if so many experts and doctors think you have ADHD not Autism maybe you should listen.
ADHD is more than just the 10 yr old hyper boy stereotype, I would recommend you just look into the referrals they want you to get, if you get diagnosed you get diagnosed if not, then pursue an autism diagnosis if you really really are convinced and possibly bring it up with the expert in your ADHD diagnosis consultation