Pixma pro 100 - Resizing and printing full images 12x12 on A3+

[shoTSby]

Hello, 

I am having trouble taking a photo and printing the entire thing 12x12 on A3+ paper. 

I am using a mac and trying to print in photos or preview - i've tried customizing paper size and defining non printable margins. If i click to fill the page I can get close to the size but it prints off center and cuts off some of the photo, I would be okay with this if i can just adjust where the central focal point is. 

A friend of mine has printed photos for me using the same printer and she was able to get the entire photo as is but in 12x12 in portrait on a3+  regardless of the photo. 

Additionally, when I use the drop box for paper it has many options (A3, A4, LETTER ETC) but no A3+ can I change that? If I try to print from my phone A3+ isn't an option there either, I'd like to add it if possible. 

Can anyone help? I've been trying to figure this out for weeks. Thank you in advance!

[jrhoffman75]

since you are on a Mac verify that you are using the Canon IJ Series printer driver and not the Apple AirPrint driver. 

I have a MacBook Air and a Pro-100 and there is definitely an A3+ option in the Canon driver.