First, welcome to the world of PMR. Never a dull moment. It is certainly a club no one wants to be part of but now that we are here, we work hard to make the best of the situation.
Your PCP means well but most likely does not have experience with other PMR patients. I am sorry you have to deal with that. I am sure if you have read many other threads you realize that the prednisone journey is very personal. Definitely not a one size fits all approach. Unfortunately, there is a national shortage of Rheumy's and every Rhuemy is overloaded with patients that deserve attention. I have a neighbor who has Sorgen's Disease and two of her three siblings also have it. They require a great deal of individual attention from their Rheumy's since treatment of Sorgen's seems very individual as well. If all of the problems in the Rheumy's wheelhouse are like this it does not take much to see how the Rheumy's are in overload.
Keeping a pain journal is good advise. It is a written history that your doctor can rely on more that your memory in the examining room. In your case possibly logging more than just morning pain would benefit you. Logging mornings pre steroid dosage, again around mid-afternoon and again at bedtime. This will help both you and your doctor "see the daily pain cycle".