Breastfeeding help

Okay I had my daughter march 2 I planned on breastfeeding but she came early and was in nicu for 3 weeks so I never got the chance to directly breastfeed and when I tried she was to use to the nipples of a bottle . So I'm pumping and giving it to her thru bottle but it seems as if my milk supply has gone down because I use to get two oz from both breast and now I can bearly got a whole oz from both . I was woundering if anyone else had tho problem and what they did to try an fix it. I've tried eatin oatmeal I've been trying lactation herbs that I got from the vitamin store and nothing's helping . I don't wanna give up on breastfeeding but I'm afraid I won't be able to provide enough as she grows