I used my vial of insulin for almost a year. As long as it's refrigerated it should be good. I think there's a tendency to suspect the insulin when in most cases it's the cat...not really the insulin. The new insulins these days are much more stable than insulin of old...although if you abuse it (freeze or leave in a hot car on the dashboard on a sunny day, for instance)...the insulin is most likely fine. Manufacturers are required by law to put the short expiration date and recommended life of the medication on there for hooman use! It's not intended for use the way we use it for our kitties...but it works great, and so we will continue to use these fine meds on our kitties.
Kit looks great btw...you're doing everything right