I tried mine on a second time and this time tried moving my arms a bit, and I think it could stand to be a bit bigger in the shoulders, too. As for the rest of the fit, it is shorter than my other short-sleeve jerseys, which I think is why it's too tight in the ribs - the elastic at the top of the pockets is too high. Maybe I have a longer than average torso for a woman? Anyway, I'm going to try again with a large.

I really like the whole "looks like polka dots from a distance, but up close they're skulls" thing.