Hi Stephen, sorry to hear about your cold nights. Here's my input, having done many sub 32 degree trips, including this past weekend where my girlfriend and I did 2 nights in NH, with lows around 25.
*As others have mentioned, you are pushing the Neoair to its limit...but that's okay in my opinion. My gf used the neoair this past weekend (for comfort) while I used the ridgerest solar. Boost your neoair instead of buying a more expensive mat. Simply add a 1/8" eva foam pad underneath it (10 bucks from prolitegear or gossamergear). This should help you boost the r-value enough to be more comfortable around freezing, and a bit below.
* EAT EAT EAT! I don't know how you're built, or what your body fat % is, but my gf and I are small, lean, folks. (I'm 5'9" 140lbs, shes 5' and ~100lbs). Simply put, we don't have much insulation naturally built into our bodies, so we compensate by eating a lot during our cold weather trips. Your body needs the calories to produce heat. A lot of people don't realize that this is the reason why they are cold at night. Because winter days are shorter, you'll probably find yourself eating dinner anywhere from around 4-6, and hitting the sack between 5-8pm or whenever the sun sets. Than around 3am you wake up shivering your a** off. Well, its probably been 8 hrs since your last meal...and its long been burned off by then. I always keep a couple high-calorie bars in my baselayer pocket (close to my body so they don't freeze). If and when I wake up cold, I eat one quickly and promptly pass out out once the warmth kicks back in. So be sure your dinner is packed with calories, and be prepared for a refresher at some point throughout the night
* Circulation- I get cold feet very easily, to the point where I'm always with my down booties. However, on this past weekend trip, I had cold feet on the 2nd night. Weird part being that the 1st night was much colder than the 2nd, and I was toasty on the first. After careful deduction I realized that the sock I changed into on the 2nd night (smart wool adrenaline's) were a bit too tight around the ankle than the smartwool mountaineering socks I wore the previous night (which were unavailable b/c they were soaked with sweat from 2 days of hiking). I removed my socks, rewarmed my feet with my hands, and stuck each bare foot straight into the down bootie. Problem solved. So check if any of your clothing is inhibiting circulation.
*Vapor Moisture in the bag...not really a problem IMO as long as you take remedial measures. My girlfriend breathes in her bag all night long, regardless of how much I warn her not to. Literally, her head will be turned to the side so far that when you stare into her hood opening, you see the back of her head. We make sure to promptly air out our bags any chance we get. So in the morning, I lay the bags ontop of the ridge of my tent, to air it out
*Compressing the down isn't much of a problem either...your bag is still relatively new and has a lot of life in it. So long as your not stuffing your bag to the point where its as hard as a rock, i'd venture to say that you have little to worry about.
*Wear all your layers to sleep. If you're cold in your bag, layer more. This includes your rainwear. You'd be surprise how much of a temp boost you get when you put on that not-so-breathable hardshell.
*Still cold? Do situps in your bag, wiggle your toes, etc etc...Down only keeps in the warmth you generate--it doesn't produce warmth on its own. So do something and make some heat!
*Fit of the bag: You have a long bag...are you tall enough to fill it up? Excess room is just more dead air you have to fill.
*Shelters/platforms are cold...its the wood/air
Also, if anything, read this post:
You'll probably find it very helpful
Hope you have better luck next time!