Low milk supply

This is my second baby and sadly im experiencing this again and it’s so frustrating. All because i was scared when baby cry so much and i wasnt producing any milk yet so i introduce fm and now i can’t keep up. Now my lo is 1month old and taking 120ml every feed. I bf before I give her fm to remove my milk. My pump output is 20ml for both breast combined in one session. I’ve been pumping and sometimes missed the 3hr timing while tending to baby and toddler at same time. Now my lo gives up easily to suck while bf and it makes me sad. I was thinking if I should totally remove formula and bf entirely once and for all & probably just let baby cry/latch for as long as she wants. Is it a good idea? Anyone done this before?