i think changing a doctor makes a huge difference. Some doctors i.e. prescribe SSRI with ADHD medication or prescribe ADHD medication only with a supervised therapy for depression.
MAybe you should check with other doctors if there is any chance to battle both (adhd and depression) with an solution that works for you.
He may have good reasons and experience why he made his decision the way he made it. But it is only one decision and you can ask more doxtors. If it seems they all aggree- he might me right- but if other doctors seems to be fine to prescribe you your medication it could be that your doctor just want to play around.
From my experience doctors are very different. In one state I got a normal dose and it worked fine for about 10 years!, but I moved to another state and the doctor cut me almost completely off and said the dose was insane- she yelled at me so I kept quit and took what she gave me but it did not work for me at all. It was a nightmare but the one doctor just did not care about me.