Two-Quart Head

I felted a hat today, first time I've tried felting anything. Ended up using an 8-cup measuring cup for the form to keep the hat on while it drys.
I tried finding a ball to use, but my head is bigger than my Pilates ball, but smaller than a soccer ball. Does that make me a medium? I was glad to hear Soozaday felted hers, let it dry, then felted it again after deciding it still wasn't quite right. Is that how that went, Soozaday?
I guess this is my New Years hat! I need to tie on a sash with 2019 printed on it.