22 days old baby girl always hungry!!

Hi...my 22 days old princess seems to be hungry all the time! Her doc said that I need to breast feed her for 10-15 mins after every 2 hours. However she starts howling after 1 or 1 and a half hour. Then right after I burp her she starts wailing again as if she hasn't been fed. What could be the reason? I'm pretty sure she is drinking milk when she is latched on as I can see milk around her lips and her jaws move up and down. Any advice will be good right now...