How to increase milk supply?

Ok so the 1st week I was able to pump total of 3oz for both sides. By the end of 2nd week I got a fever and my milk supply dropped. I was only able to pump .5 oz total for both sides. And becuz I forgot to pump sometimes at night. Now my baby is 3 weeks and I've been pumping every 2 hours or 2.5 hours hoping to increase back my milk supply. But I couldn't get it back up only able to pump 1.5 n sometimes 2 oz total for both sides. Please help? I also take the fenugreek and milk maid for milk but it's not really helping.! I also let my baby feed from my breasts here and there becuz she won't latch on it long sometimes only 3 mins or 10mins the. She get frustrated and demand milk from the bottle. I've made a mistake by giving her milk that I pumped since week 1 now going in week 4 she's used to it. Please give me advice on when to pump or how to increase my milk supply. I'm so stressed out that my baby is not getting enough milk to drink becuz she normally drinks 2.5-2.7oz per feeding :((