Definite signs of low milk supply?

My LO is four weeks old and has always been fussy when breast feeding and as of her last week check up still has yet to regain her birth weight. For the past week I have been taking fenugreek and blessed thistle and pumping/breast feeding every one or two hours with one three hour break at night. At first I could only pump one half or one oz. Now it ranges from one half to two oz. My doctor asked me to supplement and at first I thought if I just did all these things she would be fine without me supplementing. I was wrong because she would still always be fussy and crying and I know people say your breast can't be empty but the supply would still be so low after feeding off each breast twice and drinking the pumped milk she would still be fussy at the breast, pulling the breast with her mouth, and crying. I finally gave her two oz of formula after breast feeding and giving her the pumped oz and she was fine. No crying, she was alert for the first time, slept for more than an hour and didn't whine in her sleep for the first time. I didn't know I was starving her the whole time. She was having 6-8 wet and 2-4 dirty diapers. But she had only gained 5 of the 12 oz she had lost since birth. I really want to continue breastfeeding but it would be selfish to have her starving out of pride. After a week of these vitamins and hourly pumping is it time to admit to a low supply and embrace formula? If you believe my supply can still go up please let me know of a occasion or person whose has this late. Thanks.