I have flown with Virgin. I have flown with BA. I have flown with Delta, I have flown with EasyJet. I have flown with RyanAir, I have flown with ... With each airline, I have taken my insulin, my needles, and in recent years Libre and insulin pump. Not one airline has given a fig about any medication, needles, food, ... I have in my hand luggage.
In my experience the people who are concerned about the contents of my hand luggage are airport security and, on the rare occasion they have spotted my insulin, they are happy provided I have all liquids in a clear plastic bag (only liquids need to be in the clear plastic bag). In 15 years, I have only been asked for my doctors letter once and that was when security levels were especially high (due to the "shoe bomber"). However, I keep my doctors letter with my passport just in case.
I have traveled to many countries in Europe as well as North and South America, Asia and Africa.
I ALWAYS carry all medication in my hand luggage. Insulin does not like the cold of the hold but most importantly, I do not want to be separated from it. I ALWAYS take at least twice as much of everything (insulin, needles, test meter, strips, ...) than I think I will need. This is in case of loss, damage or delay. If I am going somewhere hot, I ALWAYS take my insulin in
Frio bags but I don't "charge" then until I reach my destination.
I do not take the package for my medication and have never been asked about it.
I see no reason to cancel the trip of a lifetime but many reasons to have an amazing trip. But make sure you get plenty of sleep before you go so you can make the most of your time away.