You are correct. The main problem is Cannon. They only list paper size on their driver that match what they sell. I print 11x14 because they have frames this size, but Cannon doesn't sell this size paper. In the past HP would let you print whatever size you wanted to, or what they had on their drivers. It isn't really Apple's problem. It is my trying to make a Cannon printers work like the HP printwe I have used for the last 10 years.
WE also are familiar with the older iPhoto program from 5 years ago. The newer program, in many respect, is easier to use but can be frustrated when you are not familiar with the program.
THan you