Too small

This does not look like it is going to be large enough. With my vast experience felting "booga bags" (is four considered vast?) the piece usually shrinks about a third of the original size. This slipper looks like it is just the right size now! I'll have to do some thinking on this - I am using size 10 and 1/2 cuz I didn't have size 11.... Jeeze...maybe I should knit up a swatch and check gauge!