Ok, glad to hear that your doctor did start him low and work his way up. That is the normal approach. I can also understand why your pscy would question the dose. Frankly, if he is going to be seeing the psychiatrist - I would probably go with what he is asking. Best wishes.
He has been on meds for two years. He started at 36 mgs of Concerta then 54mgs and it seemed as though it was not enough. At that point our pediatrician moved him up 19 more mgs. He seemed ok on it. If I'm understanding correct. The standard is no more than 54mgs but that every child is different.
The standard practice among doctors is to start the child out on a low dose and then increase based on parent feedback. The recommended starting dose is 18mgs and the max is 54 mgs (http://www.rxlist.com/concerta-drug.htm). Note: if your child was already on a stimulant drug, then the dosage does change based on that experience. If the doctor started him out on the low dose and slowly moved him up, then this may be ok. If your child was not on a prior stimulant med, and the doctor started him out at 54mgs, I would ditch him as fast as possible (and consider a law suit)! Also, unless your child was on a prior stimulant med, the additional doses during the day are uncalled for. Your child is at the max possible dose at age 7.
It does sound like your psychiatrist is on the right track. Personally, I always recommend a psychiatrist over a pediatrician due the the training involved.
By the way, my standard recommendation for parents with ADHD kids is to buy the book, "The ADD/ ADHD Answer book," by Susan Ashley. You will find it very helpful now and in the future. Best wishes.