Complementary H-Bridge Motor control
Since you have six I/Os, as long as you don't have to run both motors at the same time, you could parallel the like gates of the two bridges and mux the grounds to the bridges with your two remaining I/Os, like this:



The transistors and CMOS inverters are what I have in my SPICE library, and they're conceptual only.  You should select the parts which fit your project. 

If you want to play with the circuit, the model is here, and if you don't already have it, LTspice is available free.