Your list looks pretty well thought out; do you have a charging cord for that iPhone, however?
I'm thru-hiking this year, temporarily off-trail just now fighting off a bout of Giardia. I started on Feb 25th and my feeling is that you're going to be cold even with what you've modified your list to include.
I'm actually using a thermawrap jacket now, and a WM 32F rated sleeping bag and they're plenty for where I'm at (I left the trail in New York). But I started with a WM 20F bag and a Montbell Alpinelight parka, and slept a good few nights wearing both of them --- temps got down into the teens in the Smokies and elsewhere this year. I suggest you get something like the Alpine light parka. In fact, I also carried a thermawrap vest that I layered with my windshirt for walking during the day.
Because note also that during the day in the early part of my trip there were some very windy (fairly continuous wind) days, a cold wind indeed. So I liked using my earbags combined with a baseball cap, and definitely some sort of light wind-proof mitten shell Plus a good rag wool or equivalent synthetic mitten. (gloves are rubbish IMO, and unfortunately outdoor stores along the AT don't sell mittens, or only heavy/bulky ones). Don't know about a hood vs. hoodless windshirt, but very nice to have one with a collar that zips all the way up the neck.
I even appreciated having longjohns, which I normally find to be a PITA. They're handy along with shorts when washing clothes in town too, and on the coldest days I even walked with them on a couple of times.
Getting the right mix of warm clothes is a bit of a challenge, but while you could end up fine (luck of the draw with weather) with just a thermawrap jacket and a Golite 20F quilt --- I think it's pushing it a little too aggressively.