12v 25A power distribution PCB design
as drawn the switches have a better connection to negative than they do to positive. 
especially the left column (the column closest to the switched terminals)

one way to fix:

On the right side use both planes to carry the negative supply.

commit most of the red side to distributing the positive supply. 

on the purple side put the all traces that go to the switches traces and also the traces that grond the LEDs 

Keep the PTCs on the red side, move them directly above the pin they feed and rotate them 90 degrees so that they impede less of the current that comes from the top of the board. - avoid making horizontal cuts in positive part the red plane.