What you should do with pizza is give a bolus for the carbs from the bread and whatever copious toppings you put on it that might contain carbs, but you should also give a square wave bolus (combo bolus for us Animas users). The reason your number was good right after eating was because your insulin took care of the initial carbohydrates from the pizza...but your fast acting insulin only lasts for about 4 hours (peaks at 2 hrs). Your body digests the fats and proteins from food slower than carbs so when your initial bolus is gone, your body has no insulin left to combat the additional BG raise that will come from the fat/proteins.
If you do a square wave bolus (if you're on a pump) when you eat a high protein or high fat content meal, to last 4-5 hours and depending on your ratio, input a good amount of insulin to be added to your regular basal rate over that time period, your glucose will be good when you test, say 3 to 4 hours after the pizza.
Hope that makes sense. I actually just read your entire post, Jordan and saw that you're on injections. I haven't dealt with those in a good while so possibly someone who is a pizza connosieur and on injections could give a solution. Whatever you do, don't compensate for the fats/proteins with your bolus or else you'll end up super low, then you'll correct to get a 'normal' BG, but then once the fats/proteins digest, you'll be super high.
Again, hope that helps, or if anyone else can elaborate I know I'm on the right path...just a little low myself :)