Kwikpen longevity for microdosing: how long can one pen last (60/90 days)?

TL;DR: 2 months into Mounjaro (2.5mg Kwikpen, ~weekly), losing 1kg/week, want to slow down with only 4kg left to go. Kwikpen is my only option in France. Planning to microdose using half-shots from the 5mg pen, then eventually the 2.5mg pen. Question: with proper fridge storage and hygiene, can a single pen realistically last 60 days (8 shots) or 90 days (12 shots)?

Hello. I've been on Mounjaro via Kwikpen for the past 2 months, at the entry dose of 2.5mg, spaced roughly 7 days apart (sometimes more). I've steadily lost 1kg/week, but I want to slow down. I only have about 4kg left to lose. I live in France, and the Kwikpen is my only option: I can't switch medications or delivery methods.

I have Hypermobile Ehlers-Danlos Syndrome (hEDS) and fibromyalgia. I was mildly overweight, not obese. I started Mounjaro specifically to see if it would help with inflammation, and I was shocked to discover how much "food noise" I'd been living with without realizing it, since the drug cut it out completely.

I want to transition to microdosing. I know some members here microdose with the Kwikpen. I've run the numbers, and it looks like it would already be cheaper to move to the 5mg pen and do half shots, then eventually drop back down to the 2.5mg pen for half shots (1.25mg).

My main question: how long can I keep using the same Kwikpen? I'd store it in the fridge the whole time, use clean needle tips, check for cloudiness, and clean the rubber septum before each injection. I understand the "30 days after opening" guidance is about full potency, not sterility, and I'm fine with reduced efficacy since I'm aiming for a lower dose anyway.

Could I realistically stretch one pen to 60 days (8 shots)? To 90 days (12 shots)?