Irahm, which bag did you get, specifically? It might help with deciding on a loadout.
I would suggest that since this bag is going to be in support of your AR for in-town (possibly in county if things get bad enough,) I probably wouldn't look to live out of it, just support you (and the guys to some extent) for an active shooter/hostage situation. Weight is going to be key since you already have your duty belt and all the fixin's, and maybe a coat in this weather.
This is my active shooter/warrant loadout if it helps. Note: I have mine on a chest rig, since I'm a warrant team guy:
-2 spare pistol mags
-2 spare AR mags (I have a 20 rounder in the gun, 30 rounder in a stock pouch = 110 rounds total)
-IFAK (trying to figure out how I'm going to carry one in uniform)
-TQ (+ the one I carry on me in unform)
-3-4 pairs Nitrile gloves
-Spare flashlight
-4 spare AA batteries (spares for Eotech and all flashlights)
-Dump pouch/evidence collection bag
-2 pairs of flexcuffs
-Small roll of electical tape
-Protein Bar
-16 oz. "flask" of water. A "flask" because it's flat and out of the way, fits in an AR mag pouch. Camping section at Wal-Mart.)
"Maxpedition - fatboby" It really isn't too big but enough to put what I need in it.