The Page Designer block is really designed to work for a relationship of 1 RECORD to 1 PAGE. Any attempt I’ve made to disrupt the balance of that equation has usually ended in frustration.
I can’t tell exactly, but it sounds like maybe you are currently getting multiple photos that live in separate records into a grid or something on a single page. The only thing I can think of to try to help you is to suggest putting all of the photos that you want on the page into a single attachments field in the same record. Then, when you add your section for that field on the page, you can size it to cover the whole page, and it will give you the option to scale the images within the box to the size you want.
It’s still pretty rigid, and doesn’t always come out pretty, but it might get you closer.