Size of flange for Ameda PY pump?

[beep]

I am 32 weeks and have just received an Ameda PY pump. The flanges that came with it are the standard size. I have large, soft breasts with average to small sized nipples. I could fit my nipple and areola into the flange comfortably enough, but the rest of my breast kind of spilled and billowed out. Does this mean I should be buying the bigger size flange, or is it more about fitting the nipple/areola than the rest of the breast? Or is this something I should wait to think about until after I have the baby? TIA.

[lifeguard]

I have a different pump but it has only one size of flange (I didn't even know there was different sizes). I have very large breasts & have never had a problem with it not working. It covers my nipples, areolas & about an inch all the way around them & believe me MOST of my breast tissue is not in the flange. But that's ok 'cause it's meant to mimic the babies mouth & they only get the nipple & areola in their mouth.