My baby refusing breastmilk.

My baby is having formula milk for last three months. I have joined to job when she was three months old. For the first few weeks its hard to manage the milk flow during working hours. I managed nursing at evening and night time. she is six months now. for last few weeks she started refusing breast milk. and also my milk production was reduced.I tried many times feed her. but she is not ready for even sucking milk. yesterday i realised that my milk become salty taste. I am very much worried about this condtion. I cant resign my job. I am very sad because my baby is stoped breast feeding at her sixth month. Feels so bad I feel like to cry when she refuses milk. and low prodction of milk. Please any one tell me how to increase breast milk. and how to breast feed my baby...