Less breast milk. My breast milk!

My breast milk supply is very low.i had emergency c sec on 19 june 2022 (preterm -34 week 5 days,weight -2.480) after that baby was in nicu till 21 june(only first 2 hrs on oxygen support&rest two days for confirmation of blood culture and observation since I had feverat the time of operation) where they made her to drink Nan pro formula paladai milk,after coming to home she had difficulty in latching since I have flat nipples tried nipple puller and nipple sheild some times she drinks some times she don't.now she is able to suck atleast through nipple shield but milk is coming in very less quantity.sonshe is getting fussy and I m continuously giving formula feed and topping that with breastfeeds when ever she is interested that too only one breast.so I started pumping at least once daily i m hardly able to get 2-4ml from that non side using breast and other side atleast 10 ml in addition to giving feeds atleast 3-4 times 10 minutes in a day.what are the ways to increase my breast milk