Not much milk flow in my right breast.

Rebecca
My daughter is 11 days old and I am not producing enough milk so we are having to supplement as well. She nurses on both sides for 20 mins each, then gets 2 oz of supplement. This seems to fill her up. 
Whenever she feeds on my right breast, she seems to struggle with getting the milk to flow and gets frustrated pretty quickly. I decided to pump one feeding out so I could see exactly how much I am currently producing. My left side produced almost 3 oz of milk, while my right side produced only .5 oz. How do I know if I have a blocked duct? Anyone have any advice? I've tried using warm compresses and hand expressing but I can't get anything to come out that way. My right breast has yet to be completely emptied and I'm worried that it might cause damage to my breast.