"This kilt is too small ..." she said

[xman]

You may have measured too tight on both to start with.

This certainly happened.

What are the measurements you used originally for the kilt, and what are the splits that you used between the apron and the pleats?

waist - 17.5" - split - apron 9", pleats 8.5"
hips - 19.5" - 9.5" apron, 10" pleats

What measurements do you get now when you measure him loosely at the hips over pants and only lightly snug at the waist over a shirt, in inches?

Now;
19.5" waist
21" hips
I should say that I've taken Steve's advice and put two fingers in the tape. What I meant by my last post was that this STILL seems inadequate.

If you lay the kilt out without stretching, what do the pleats measure at the hips and waist, in inches? How many inches is it across the apron at the hips? What about at the waist?

Now that's tough because I've now got 22 pleats including those that will be hidden, 20 with full deep and reverse pleats. Pleats are five and a half 'plus' at the hips and four and a half 'plus' at the waist. I'm going to go with either eighteen or twenty pleats for now and hide the rest. The apron is currently 10.375(3/8) at at the waist and 10.875(7/8) at the hips.

[Edit] I'm starting to feel like I should just work in metric. We're kind of stuck between the two systems here in Canuckistan.