I'm so frustrated right now.. my milk supply has dropped so much that my left breast is almost dried…

I'm so frustrated right now.. my milk supply has dropped so much that my left breast is almost dried up..

my baby has always nursed on demand, I pump usually twice a day, and she has never had a drop of formula even when the idiot doctors sent us home from the hospital saying that we "needed" to supplement with formula. so I don't understand why this is happening.