actually never book a return flight unless you don’t like your life or money. I’m a full time traveller for 12 years and never buy a return flight in that time. What some airlines from some locations insist on, is proof of ‘onward travel’ which proves to them that you intend to leave the country within the time limits of your visa
use a local agent in your area (so you can have assistance available when needed) that can access a major carrier like Allianz or Axa. At 67 it won't be cheap and worse at 70, but worth it.
use Remitly if you are angry at your own money. You always get a worse exchange rate. They charge ‘lower fees’ to prey on the financially uneducated. It’s a good strategy