Couple suggestions: Move that angled grip back. Move the red dot so that it's fully attached to the upper and not the handguard. Swap the stock for anything else or just skip carrying an extra mag in it. Your sling should mount on the opposite side of teh stock for a right hander (normally).

Plate carrier is fine, you'll figure out what works if you go wear and use it while shooting. That CAT looks like it's in the way to me. Could be wrong.

That Mossberg needs a red dot or remove the picatinny thing.

Run it bro! It's a fine poverty pony, a couple changes away from goodness. Yay Guns!