Sis, totally normal! EBF babies can actually go anywhere from a few times a day to even 5-7 days without pooping, breastmilk is just so efficiently absorbed na walang maraming waste. Someone in my mum group mentioned her baby did the same thing at that age, and her pedia said as long as baby is happy, gaining weight, and wet diapers are regular, it's nothing to worry about.
The thing is, yung fussiness or discomfort can be about other stuff too (teething, growth spurts), hindi always poop, so it's hard to tell sometimes. Good call na may scheduled pedia visit na, mas mapapahinga ka ng loob once doc confirms baby's doing fine! Just keep an eye on those wet diapers and baby's mood, and you're already doing great.