feeling lost

Hd
I feel so bad for giving my son formula. He's now 2 weeks old and he consumes around 2.5 oz every feed and I make only 40ml milk everytime I pump. I'm drinking lots of water and taking fenugreek too. Nothing helped in boosting up the supply so far:( I was making around 2oz last week and I have no clue why milk produce dropped all of a sudden.