My baby started drinking 180mls at abt 6 weeks old, (he's abt 11 weeks old now) but these couple of days, his appetite seemed to have decreased. He's almost sleeping through the night or only needs 1 feed though. Is this normal?

Hi girls, sorry been so tied up with lo & havn't had the chance to log in but thank you all for your prompt replies! Yes, 180mls seems alot but his pedaetrician assured me it's ok & that my son's just got a big appetite (which will decrease eventually & it did!). He's still drinking 180mls max now at 13wks, some days less. Anyways, his appetite did resume few days after my initial post above so phew! However, he seemed to be sleeping alot these 2 days thus his feeding time's stretched (can be 4 or 5 hrs after the previous feed). His bowel movement's also different now. He used to poop everyday or once every 2 days at the worst, but he's been only pooping once every 3 days now (for 3 cycles already)! I've tried belly massage & bicycle ride exeecise but that haven't helped. Any advise?