My 7 mo old son will sit assisted, but still can't sit on his own. I have gotten him to the point where I can hold onto his hips while he is between my legs (barely supporting him) and he can sit and lean forward to grab a toy and prop himself back up with his core muscles. He will also lean forward in his bouncer in a seated position.
However, he does not have the primitive reflex of sticking his hand to the side if he starts to fall toward one side or the other.
I know that 6 mo is the avg age of sitting unassisted, but what is the age range of normal for this milestone? At what age should I start to get concerned if he is still not able to sit unassisted?