Why won't my son's doctor listen to me?

My son was diagnosed with ADHD at age 5.First by the school,Then by a Psychiatrist.(he's now 7 and in 2nd grade) I have always felt that they are wrong,because my son acts odd.and have alot of the symptoms of Mild autism.He has socail and behavioral issues,repeats himself often,says off the wall things all the time.He does not handle change,or being away from me for a few hours,he becomes upset and very stressed if im not around.Also he hates noise,loud sounds,dosen't respond to pain and other odd behavior.I've been pointing out these behaviors yet get no change in diagnosis,even his teacher has told me in her 21 years of teaching and seeing many kids she has yet to have a student like my child.she also told me she dosen't feel it's ADHD and to keep fighting for my son.another thing my son is super smart.When tested he has superior IQ or something like that.How can i make his doctor understand that this is what i believe is going on with my son? They just won't listen and want to put him on meds that make him angry,resentful and depressed.(almost suicidal) I don't want that for my son.