EDIT: SORRY WRONG BOARD!!
I have Medela & I just have the standard 24 mm. I was a going to buy a size bigger, but then got on to
the https://www.medelabreastfeedingus.com/assets/file/PF chart.pdf
website, where it shows you pictures of how your breast shield should fit.
I'm thinking I need a 21 mm, but I heard you get more milk with the larger shield, but I'm assuming when people say that they don't mean a "larger" shield but rather a correct fitting shield. But I don't want to spend $15 on 21 mm & then my pump session produce less.
I just measured my self & I'm a 34C right now. Has anyone else experienced this? Did you buy the smaller size & did you have more or less when changed? Thanks!