Increasing supply?

How can I increase my supply? Baby is nursing every 2 ish hours and acts full when he's done nursing. He's almost 3 weeks old, and having issues putting weight on and the doctor wants me to supplement with formula. I really don't wanna supplement with formula at all (I'm not anti-formula, just wanted to exclusively breastfeed.) So I've started doing that to see if it helps him put weight on. Haven't been back for a weight check yet, we just started today. He acts hesitant toward formula like he doesn't want to drink it. Just need tips on increasing my supply so we can get back on breastfeeding. I've tried fenugreek and could not stand the maple syrup smell, and never noticed a difference in my supply.