I'm in for Civil War, too.
I also cut mine just like Sheri. If they're not at least 18" x 22" it's because the fabric isn't exactly 44"-45" wide. Also if anyone buys pre cut fqs, or your lqs cuts them, they may not be exactly 18" x 22".
But I absolutely try to make sure mine are at least that size.
Regards,
Kif