Honestly, this is just how it goes sometimes! Frustrating for sure, but everything you're seeing is pretty normal.
Since she apparently didn't go too low last night, I'd hold the 1.25U dose. I'm actually a bit surprised at such a small difference between PMPS and the +5.5. The recommendation for Vetsulin is to hold for at least 5 days unless she drops below 90 again, so do the mid-cycle spot checks when you can. Then a curve after those 5 days, and decide whether to increase or decrease.
I will say her big drops every now and then so make me a bit cautious...so although last night was ok, the next time you have a lower PS and shoot might have different results. If you can at least make sure she has food available in the +4 to +7 timeframe that will help.
As for Mr Kitty, I'm not seeing any difference yet. He was just one of those cats that did well on Vetsulin at the start, but I was a bit concerned about how harsh it would be over time. Right now I suspect I have glucose toxicity to break through, so I probably won't see any improvement until I hit 4U or more. Then hopefully we hit a breakthrough dose, and I can start doing reductions.