How to position objects on screen?

[Gasmansteve]

Hi guys
I`m going round in circles for what should be (I think) a simple task. I have created 9 different objects all 75mm x 25mm and saved them as jpg files. I want to be able to print these on an a4 piece of paper. I create a new a4 portrait and then open one of the objects and thinking I could just copy/paste this onto the a4 sheet at actual size doesn`t seem to work as the objects look much bigger than they should be and I want them to print the correct size.
I used Affinity Designer to create the objects and now wondering if I`ve made them the wrong size?.
Hopefully this shows a grab of one of the 75mm objects on an a4 form
thanks
Steve
forgot to say the 9mm just refers to the circle diameter and I`m using xp&gd and also xara page&layout