Ebf baby’s digestion

So my baby boy is 4 months old, and I’ve always had concerns about him pooping. He used to grunt, and cry really bad when he had to poop, and had gas, which was pretty much everyday, and my pediatrician told me he was just learning how to poop, after about 2 months he stoped that, and started pooping every 3 days which I thought was great because before that he was only pooping one a week, but then he went back to only pooping once per week, and now he’s not pooping. It’s been a week, and 2 days since he has pooped. He has a pediatrician appointment Thursday. Is this normal? Should I be really concerned? He’s pooped a tiny bit to where it showed up just a little on a wipe, but other than that nothing, and I’ve even been trying prune juice.