Every baby develops at their own pace. Not sitting independently, still having the extrusion reflex, and not grasping at 6 months is within normal range. Green poop in exclusively breastfed babies can result from getting more foremilk than hindmilk — try keeping the baby on one breast longer. The US CDC Milestone app provides evidence-based timelines that are less anxiety-inducing than most milestone apps. Some babies with silent reflux reach gross motor milestones on the later end. Always consult your paediatrician for reassurance, but avoid comparing timelines between siblings.