Ay hindi ka nag-worry lang, normal talaga yan especially pag mixed feed kasi mas mabilis ang digestion, a few of us here had the same concern at first! Kasi breastmilk alone, okay na 5-8 times a day, pero pag may formula pa, it varies din based sa baby's system, so it could go down or up pa depending sa day. Siguro lang check mo if the poop consistency is still normal yellow/greenish and soft, at kung hindi siya fussy or may fever, you're probably okay lang, pero if you're really uneasy or if it continues differently pa, better check with your pedia just to be sure, okay?