Ay, at 3 weeks old, baby should be taking around 60-90ml per feeding if bottle-fed, pero talagang depende sa baby, some ng babies namin take less, some take more, kaya follow mo lang kung gaano siya gutom! The best way is to watch if baby's gaining weight properly at may wet diapers throughout the day, pero definitely check with your pedia para ma-monitor properly kung kumakain siya ng enough, lalo na if breastfeeding kasi mas mahirap i-measure yung intake.