Problems H-Bridge on PCB taking all the current
Do your self a really big favour and avoid disrupting the ground plane you have on one side by minimizing things that don't need routing on it. For instance, a few simple modification can achieve this: -

I've just taken your image into paint and redrawn blue tracks as pink tracks. The pink tracks can go on the same PCB side as the red tracks and that means a much, much better ground plane.
Also, as per my comments, there is a complete absence of power rail decoupling capacitors.
See also this Q and A that addresses many problems that the L293 motor H bridge faces on low voltage supplies. In short, try to avoid using it because it will get very warm and burn on motor currents more than a couple of hundred mA.