My thoughts were the same as Sue's. If there's any way you can grab a test even it it's at +2 or +11 on the evenings that you're working. (We're more used to seeing people working days vs nights. Many of our newer members don't realize they should get PM cycle tests. We do understand how work can interfere with your managing Myrtle's diabetes!)
Basically, what bounces are all about is a large or rapid drop in test numbers. So, if Myrtle were to drop into low numbers, if she had a big drop (e.g., 400s to the 60s), or a fast drop (vs a gentle slide), there's a high likelihood her numbers would spike into a high range. The mechanism behind a bounce is that the liver and pancreas, in response to the drop in number, does into "panic" mode and releases a stored form of glucose along with counter regulatory hormones. This is what causes the spike in numbers. In can take roughly 3 days/6 cycles for the bounce to clear although once your kitty becomes used to spending time in lower numbers bounces are less frequent and clear more quickly. Bounces are a normally occurring, protective response that annoys us but is not dangerous or unusual.
Given that Myrtle isn't new to diabetes, it's less likely that she's bouncing. I'd also be reticent to suggest reducing the dose unless I can see a documented drop into reduction worthy numbers. Your signature doesn't indicate which dosing method you're following. Have you been able to decide?