Establishing breast milk!

My son can't latch on because I have inverted nipple, I used a nipple shield, he still didn't latch on, my milk supply dropped soooo low it's not even a half oz. I really need help! Please I really wanna breast feed, I'm trying to pump, I tried power pumping, I just started taking Fenugreek pills, 3 pills 3x a day, hopefully I'll see improvements, trying to higher my water intake, but if there's any advice please I'll love to hear it ❣