Low supply breastmilk

Hi, im a FTM, currently baby is 16 days old. Everytime when i tried to latch him, im only managed to latch for ard 15 to 20mins. And he will asked for milk again after 1 hour. Lactation consultant said it may be because of wrong latching position of due to my breastmilk supply not fast enough. I tried to pump out for 30mins and only managed to get around 40 to 50ml milk (total left & right) which is not enough as his feed is 60ml. Usually pumping the milk comes fast during first 10 to 15mins but i realised it slow down after which. Anybody facing same issue as me?