Suggest Treatment For Low Milk Supply

Question: Hi my babiy is full month born with normal delivery, as of today she is 3 months & 5 days, her birth weight is 3.07 Kg , on the third day of her birth she was said to have jaundice and so was treated at the hospital with photo therapy and got discharged in three days, after she became 15 days old, she was passing lots of water still frequently and so we consulted another doctor, as our present doctor was seemed everything to be normal.
The new doctor said that she is infected diarrhea and so we admitted her for 15 days, later she was discharged and thing were Normal, but my baby was not gaining weight, her growth in first fifteen days was 400gms, but after diarrhea her growth was 10 gms a day which went upto 20 gms a day and again reduced to 12 gms a day, after she completed two months, she has passed watery stools for few days twice a month and even after she completed three months we tried to give her formula milk with low lac as doctor suggested, but when we gave her for the first time again she started passing watery stools with a frequency of thrice a day, her current growth as per three months five days is: weight 4.6 Kg, height: 63cm, head circumference: 37.5cm, is her growth normal as per her age and birth weight?? Also please advice us what shall we do to avoid doing watery stools, gain weight and also shall we continue formula milk with low lac?? My wife will be resuming her work with a week after 7 months leave, now we have no option but to resume work, in this case how shall we take care of her feeding and also suggest, how my wife can produce more milk as the production of milk is reducing.???
Awaiting your reply.