Hi scientist,
My name is Rosie and I am a cancer nurse working with the helpline team at BCNA. How exciting to be thinking of an overseas trip even while having to consider the issue of travel insurance! Great to hear you are feeling young and healthy and responding well to your treatment. You may be aware of this information but I'm including the link to the information from the BCNA website as it is very comprehensive.
https://www.bcna.org.au/metastatic-breast-cancer/coping-with-metastatic-breast-cancer/where-to-find-support/travel-with-metastatic-breast-cancer/I'm looking forward to seeing what tips and advice you get from the other women. I hope you can enjoy the planning as that should be part of the joy and anticipation of travelling. :)