Good on you to pull the trigger and not agonize forever on what to buy.
A couple of accessories to consider...
Besides a fleece stocking cap (toque) the single item that will give you more warmth for its minimum bulk and weight ratio is a fleece neck gaiter with a flap down the front and back. I have cut the sides of a long tube neck gaiter to achieve the flaps, which came standard on my favorite Turtle Fur neck gaiter. You can pull it up over your ears to meet the toque, take it off when hiking and getting too warm, put it back on when you stop. It will allow you to wear your current system comfortably in considerably colder temps than you can without it. With the hood of your outer parka over neck gaiter and toque, you can handle some pretty deep cold. Loose clothes a little on the too big size are better than snug, and allow you to add additional layers.
Another item I LOVE is a pair of wristlets made of thin fleece Turtle fur. They are merely a tube with a thumb hole. The tube extends from the base of your fingers past your wrist and well up your forearm, and the fleece is thin enough to wear a mitten or glove over it. It leaves your fingers totally free. It would be easy to make this item though I never have.
If you can keep your wrists warm your hands stay warm much easier. Ditto for neck and top of head to keep your whole body warm, including feet, though that is old, old news I'm sure you know.
Five years is a long time for my outer shell to hold up well. I sleep in them in the bush, sometimes without sleeping bag, wad them into a day pack, chafe them with pack straps or a quarter of meat on my shoulder, bust brush while wearing them, sometimes bust brush loaded with snow, and often wear them through wet brush and wear them while they are drenched all day. My outer shell takes some abuse. About five years or so is when I buy new and relegate my experienced jacket to town use or give it to my daughter who loves it for suburban shopping and kid soccer games. The jacket usually still looks pretty good but is not up to wilderness performance.
