Pump often
Every two hours and at least once or twice at night. Do you have a good electric pump? That helps too, pumping both breasts at once. Drink at least 64oz of watet/healthy fluids. Relax, massage your breasts while you pump, oatmeal and carrots help, there is also a vitamin called fenugreek, there is also brewers yeast, mothers milk tea all affordable. You can try talking to your dr but prescriptions for milk production increase depression as a side effect so make sure you exhaust all options before resorting to that.
I put brewers yeast in smoothies. There is another herb that helps but I can't remember the name. Think about contacting a lactation consultant they are really helpful!