Here is some info in how much total EBM a baby should have per day:
The research tells us that exclusively breastfed babies take in an average of 25 oz (750 mL) per day between the ages of 1 month and 6 months. Different babies take in different amounts of milk; a typical range of milk intakes is 19-30 oz per day (570-900 mL per day).
from kellymom.com/bf/pumping/milkcalc.html
Our pedi recommends consumption of 5 oz per kg per day
not sure what else to recommend you, it's tough!
My milk supply is the lowest at 4-5 pm. I am feeding twins, so at that time one baby gets both breasts and the other gets a bottle of EBM pumped earlier. I get the most milk at night when the BF baby sleeps for stretches 6-4-4 hours.
I had some struggles with production before they were three m/o and am still on the edge since I have to pump for the baby who would not BF.
I pumped a lot and took fenugreek - I am still taking it, but it gives me diarrhea, so I go back and forth on it.
Good luck and let us know how it goes. Even a little breast milk in addition to formula is great, so please keep trying!