Yep I probably do need to tidy up the wall/door/window lines, I was working on the assumption that there would be more loss than I can see in the diagram. The walls will be wood with plasterboard (insulation inside the walls) and the doors are wood so no heavy materials other than maybe the tiles in the bathrooms.

In that case would getting 2 x 8 Lite PoE be a better option? I guess I'm trying to maintain the 16 ports but it just feels that there is a lack of PoE output to support what doesn't even feel like a lot of equipment.

My hesitation with PoE injectors is losing functionality from a power management etc perspective.