Repeat after me: I am not a pest, I am not a pest.
Michelle,
We have all been where you are. After the initial getting started phase, then comes the sometimes scarier dosing questions phase. You have the bg information but aren't sure what to do with it. We are happy to help; we are all paying it forward from our newbie days.
Sounds like your plan is good. Most - but not all - PZI cats have a nadir somewhere between 5 - 7 hours after the shot. The new PZI you are using may have a longer "hang time". So hope you can get some numbers during the day. Be sure to also note anything that might be influencing the bg - playing alot or very quiet, when ate and what, etc on your spreadsheet.
You are doing great!