Yes there are many mummies who have been unable to breastfeed for long due to illness, work etc. Have your tried using a pump? You might want to try pumping every 2 hours and continue to eat and drink well. Over time and with patience, your supply should increase. Try green papaya soup as well and lots of fish. Fenugreek is supposed to help increase milk supply.
You also need to have good sleep and enough of it. You mustn't let yourself become upset or emotional (sometimes easier said than done!). A foudn that all this affected my milk supply as well.
Even if all this doesn't help, feeing your baby FM is the best you can give him in the circumstances and you should focus on his other development, as well