My wife and i do a pretty good job of firming up and handling what's in our control and leaving the rest to the airlines, hotel and rental car company.
Sorry you're having these issues.
Your travel is international and more complex.
But i recommend evaluating what's in your control and whether you have properly made all arrangements and then accepting that the part of your travel plans which aren't in your control do not merit your worrying about them.
Travel has always required an ability on our part to roll with the punches and keep in mind that certain things (e.g. connecting flights) are entirely outside of our control.
I hope this helps.
The vacation anxiety i experience is going to a fun venue and having to work via cell phone and internet for a good bit of our trip.