Ugh! I feel for you, I've been going around and around the ignorance mountain. My son was a year old when the topic of Autism came up. His pediatrician did refer us to a diagnostic center, with a waiting list of 6 months to a year, and tried to pressure me into a "wait and see" approach. WELL, I didn't wait, and instead I went and referred him to the county MYSELF and he qualified for speech and occupational therapy and a special ed teacher with Early Intervention. They now come to the house every week free of charge. Thank God I didn't listen to her, because we could have lost at least 9 months of therapy during that time! Not to mention, the county was able to get him bumped up on the diagnostic evaluation waiting list, so now he'll have that done about 5 months sooner.
My advice - follow your gut instinct and do whatever you need to do to get the services that you know your son needs. If this means getting a new pediatrician, or contacting every local autism agency in the county, do it.