It looks like your kitty is pretty sensitive to the prozinc too, Frog has been lately too, the tiniest drop I can give him with any accuracy drops him like 100+ points some days. I would suggest you try learning to do the drop method, and yea, if you're not already using U100 syringes, I strongly recommend it, so much easier to measure teeny amounts. I have the conversion chart saved and can re-post it if you need it.
I have posted it here before, so you might just be able to search for it (dose_conversion_chart.pdf was the filename)
I've been winging Frog's insulin in a very similar way as you, I just am using much smaller doses, and lower thresholds, but I do try to stick to the 12 hour schedule still.
With my crew its really impossible for me to figure out exactly what and how much of which type of food frog eats, I wish I could afford to switch back to the yazc, they all liked it so much more when they had control over when and how much they ate, a lot less contention in the house then too, plus I always knew exactly what, if not necessarily how much, food Frog ate. I realize most people here are adamantly against dry food, but I felt like my cats drank plenty of water and were better hydrated with the yazc than they are right now with only fancy feast. All that said tho, wet or dry, if you do have to skip a dose, be aware of what food you feed, lower carbs are better at that point just to kind of coast back to a safe shooting range. (a good time for fish imo)