My Baby Is 16 Months And Is Still Not Saying

My baby is 16 months and is still not saying specific words, she babbles a bit and can say something that resemble a hi when we say hi, she can differentiate between ball, book and know looks at the thing we ask her to show (fan, door, dogs by name etc), is this normal, she doesnt say mama or dada..(but she knows who we are when asekd and looks) when should we expect some verbalising?Apart from all this she has some motor delays, her head is not 100% steady and only now is she sitting up on her own, but falls down in a few sec..