Hi mama! Two days is still within normal for a 4-month-old on breastmilk lang, some babies go 3-4 days without pooping and it's totally fine, kaya don't worry just yet. Check lang if baby's belly feels soft, hindi bloated, and she seems comfortable and her normal self, kung ganyan talaga, she's probably just digesting well. Pero pag may 5+ days na or makita mo siyang uncomfortable, straining, or may hard stool, best to check with your pedia na para peace of mind mo, especially since every baby's different. A few of us moms had the same worry at that age and it turned out nothing, pero better safe than sorry lagi talaga!