Need pumping shield size help!!!

Jess • pround momvof two beautiful boys
So I measured my nipple like it says to do here and I got 30 millimeters so the numbers on the chart or a little confusing to me I'm not sure which Shield I'm supposed to get and I'm not even sure I should be getting anything other than a size 24 Shield but I notice everytime I remove the pump I'm soaked like all the milk puddles up down underneath and like around the shields so my entire areola is sopping wet while I'm pumping