Girls, at what age did your children start rolling over and crawling? …

Girls, at what age did your children start rolling over and crawling? My son is 6 months old, at 4.5 months he started rolling on his belly, and now he's lazy and doesn't want to do it, often cries and cries. We had torticollis and hypoxia. Now everything is fine, but the baby just doesn't want to, constantly wants in my hands. My friend's girls developed earlier and at 9 months they started walking, I thought maybe because of that, but my nephew is 6 months old already crawling. What should I do? Should I be worried?