12 month old - she can roll and has good head control, but can't sit up unaided, can't pull up to stand, can stand if hands are held but not if I let go, can't hold herself up on furniture if pulled up. She smiles, laughs sometimes and makes eye contacts but is very quiet, no babble or words/attempts at words. No shared attention yet either, doesn't show me things, point or follow my points, look at me for reactions. It is being monitored by health visitors but at what point would you start to worry? It's very much a wait and see sort of situation at the moment but she seems much younger than other babies her age