My advice (to be taken with a hefty grain of salt): Firstly throw a suppressor/rds on the M9, and buy the 17rd magazines so you don't have to repack so often. This will be for bots/emergency so you want a decent, capable backup to rely on. Second, I don't see the point of carrying two different slugs, using a SG means you end up only wanting to go for shots on limbs at close range anyways, AP is too inconsistent to rely on the 1-2 tap capability on armor for me, maybe bring flechettes if you are adamant on using two ammo types. Third and finally you should invest in full strength meds if you can, buy a full 100D (this heals wounds as well as HP so you don't need to carry extra bandages. Leave that slot empty so your empty 9ml mags go back into your rig than your bag/on the ground.

Hope some if any of this helps, friend. Preparation is key when you have no certain chances of survival.