Note that you if you wish to use PMOSFETs on the high side, and are not using a floating gate driver then the maximum working voltage for Vcc is Vgs of your PMOSFET, not Vds like normal. Look at how much voltage appears on the gate pin when you pull it down to turn the MOSFET on and note the voltage difference between gate and source when that happens. Doing it this way usually limits your motor voltage to 10V (maybe 20V) due to availability of parts).
BTW, the only reason you would use a PMOSFET is to not need a floating gate driver. You would never use a PMOSFET with a floating gate driver because a floating gate driver would let you use a NMOS which is more efficient and readily available. Usually 20V is the highest voltage you can find for the gate-source voltage on a PMOS.
In your case, you are already using opto-isolators so if you added two more optos and zener diodes (to make a supply referenced to Vcc that dips below Vcc), you can use the opto along with that supply to make a floating supply for your high-side transistors which would let you use all NMOS.
I attached a sample schematic of what I am talking about but with a PMOS. Do you understand what's going on? The zener and resistor make a voltage regulator that dips below Vcc, and is referenced to Vcc (instead of ground) to provide a voltage between the source-and-gate pin of the PMOS. The opto is an opto so it can drive it just fine. But this circuit is a bit pointless because you can do almost the exact same thing to let you use an NMOS in the top transistors. I made this schematic in about 5 minutes so I might have missed or overlooked something. Don't use it blindly (technically don't use it at all. Modify it so it works with a NMOS).
Also, don't forget high-speed flyback diodes (like schottky diodes) in anti-parallel with each MOSFET drain-source, or your transistors may get damaged everytime current is interrupted across the motor inductance which will produce a large votlage spike if the current produced by the collapsing magnetic field has nowhere to circulate.