Trouble printing out correct photo size on iMac

Hi,

I'm using macOS High Sierra 10.13.5 and have been printing out photos using a Cannon MG3050.

The trouble i'm having is when i pick a photo from my library and select print a window comes up to select size and to Fit, Fill, Custom, 20x25cm etc.

When i'm looking at this none of the photos fill the whole space so, when i print out a photo i have to cut the area it didn't fill even when i have clicked on borderless and fill. It's not the printer as the window where you choose size, photo paper and boarders or not is just not reacting. I've tried to change size in paper handling to "scale to fit paper size" and paper size (4x6 for example) then when i press print it still comes out with an uneven boarder.

This is what I'm seeing:-

Any help would be much appreciated

- Martyn.