Uh, you're making an X-Kilt....not a masterpiece of the traditional kilt makers art.

You're banging out a simple wrapround garment with box pleats, and learning from the process. Quit stressing out over it so much, find some halfway decent fabric for cheap (which you already have), get out the chalk and go to it.

If this stuff is flannel, that won't work. If it's shirt weight, that'll be a bit light. Otherwise, just make the thing!