Hi,
The thing that increases your supply? A baby.....but that doesn't start with m. As the others have said, there is nothing wrong with your supply. You just need a little practice, and get a bit savvy about expressing. Hotest tips....try when you are fuller (but not rock hard!) Get baby to feed from one breast (that will stimulate your letdown refles) then express from your other breast. It'll work! What sort of pump have you got? The same one as you used with the last baby? Seals can deteriorate between babies rendering your pump inefficient