Flange size does make a difference (this is from an underproducer.)
Maymom Flange Inserts 19 mm for Medela, Spectra 24 mm Shields/Flanges, Momcozy/Willow Wearable Cup. Compatible with Medela Freestyle, Harmony to Reduce 24mm Nipple Tunnel Down to 19 mm; 2pc/Each
Super helpful and organized if you have to go back to work before BF journey is done.
mommore Breast Pump Bag Diaper Tote Bag with 15 Inch Laptop Sleeve Fit Most Breast Pumps Like Medela, Spectra S1,S2, Evenflo