Sizes are ordered Alphabetically instead of normal size order

Hi,
So I purchased the plugin so that I can use image swatches for the product filter. The thing that is displayed in the images are sizes from xxs-xxxl. Instead of listing them normally as xxs, xs, s, m etc., they are listed alphabetically l, m, s, xs, xl etc. Is there a way to reorder the attributes for the image filter?

Thanks

https://wordpress.org/plugins/woocommerce-products-filter/