Great story! Good on you.

Do check out kilt strap extenders. Know USA Kilts and Celtic Croft offer them. That's how I solved the battle of the bulge for my hand sewn kilts. Does look a little different to have two buckles showing, but kinda fits in with the metal look, or you can wear a sweater and cover the extensions.

Kilts hold their value and you might consider selling the too small kilt and using the proceeds towards a larger kilt. I've done that too. Works. No jones for the buyer.