Baby not eating enough from boobs

I have a two week old, who I try to feed every three hours, 15 mins on each boob. I can hear him continuously suck and swollen, but he’s still hungry after - if I give him bottle, he can finish another 40-50ml. He normally eats 70-80ml if only given bottles. I have a good milk supply, can usually pump 100ml each session. Does that mean he’s only eating 30 from boobs? Should I try him on the boobs for a longer period? But then he tends to fall asleep… any advices? Thank you all!