The fit of the flange for your breast pump can make a big difference in the amount of milk you pump and the comfort of pumping. If possible, have an IBCLC assess your flanges while pumping. This isn't always possible so here are some tips for self-assessment.
Your flange is TOO SMALL (left side of graphic) if some or all of your nipple rubs on the tunnel of the flange while pumping
Your flange is TOO BIG (right side of graphic) if more areola is drawn into the flange with your nipple
Your flange is JUST RIGHT (center of graphic) if your nipple moves freely while pumping and not much of your areola is drawn into the tunnel