Instead of making 8 of one size perhaps make 16. Let that fly, when you're out of one size, take orders. Beating the size demand is impossible. If customers love your work, they may choose an alternative fabric. They understand you are not importing by the thousands.
Customers are very nice people.
Hope this helps. I make childrens clothing in about 6 different sizes and 12 fabric choices. Since I sew on allready made denim overalls etc. This Discussion Group is monitored regularly. Any posted messages soliciting products or services will be removed.