I bought the set and... wow, things are different!
I am trying the smalle flange, the 13mm, and the pump is now effectively just sucking my nipple and not my entire areola. It's a huge difference. I admit I love the feeling of some areola being sucked in, but this is definitely exercising my nipples in a completely new way.

I wonder if there is a progression where at some point I will need the bigger flanges, or if the nipple remains the same. Next week I'll try with increasingly larger ones and see how it goes.

Thanks again for showing this to me!