Issues when printing a jpg file that has been created in Photoshop.

Wonder if anyone can help.  I am having some issues when printing a jpg file that has been created in Photoshop.

What I have done

1) created 6 individual psd files, which each are 4.5 x 4.5cm and each contains multiple layers.

2) merged the layers in each individual file.

3) created a new blank canvas and dragged & dropped each of the merged layer files into the new canvas.

(If I print directly from Photoshop at this stage, the boxes all print out at 4.5 x 4.5cm.)

4) In the new canvas, Save as Copy and save as jpg

5) Print this new jpg file directly from the print function on my laptop and the boxes all print out at 6 x 6cm

If it helps, I’m using an Epson ET-3850 for the printing. 

I spoke to Adobe live chat and they suggested the issue was with the printer, so spoke with Epson and went through some trouble shooting with them which they said should fix things, but doesn’t.

Just wondered if anyone else has had similar issues and knows a work around?

Many thanks - Kathy