Any way to hack a flange size? Does this look too big

So I think my LC measured my flange size wrong...... Womp.

She told me to get a 21mm even though my nipples measure 15 mm at the base. This is too big right? I feel like a 19mm is more my size. (Pic below)

I have placed an order for hopefully the right size but it’s going to take awhile to get here. This is a long shot but is there a way to make this more comfortable while I wait for the other flange to come in?