Yeah, the problem is coming because from the perspective of many kiltmakers you are still in a young persons kilt and not yet in the range of sizes that most adult make kilt wearers call home.

I would not recommend moving buckles to take in a full 4 inches. That seems to be a bit too much.

You might try contacting a kilt rental place that rents children's kilts. They sometimes sell off old rental stock and you might be able to find a bargain that way.

And don't feel bad about being your size. As I'm getting my groomsmen sized for my wedding, a 34 year old groomsmen who just happens to be in great shape and rather short is having to get a children's kilt for his rental!