Supply problems

I started taking the mini-pill about a week ago and about four days ago my supply plummeted. The only thing I can link to the supply dropping is starting the mini-pill. After reading online that could be a problem I stopped yesterday.

I only have enough to feed my son during his first night wake up (after he has slept 4-5 hours) and when he first wakes up in the morning (after another 3 hours of sleep.) After that I try to feed him until he gets too cranky, then give him a bottle. Unfortunately I am out of the breastmilk I was storing, and have had to give him formula.

My question is: I bought some Fenugreek 620mg capsules. How many should I be taking to best increase my supply? I am drink much more than 64 oz water every day. After he finishes feeding with me I am pumping for at least 10 minutes. Is there anything else I can do to get my supply back up? Feeding him formula feels like I am failing him, but I can't let him go hungry. I don't want to give up on breastfeeding, so please help!