I don't think Jace looks particularly big for a child of his age, but nor do I think he is tiny either nor do I think he is behind or advanced. I have known cousins and friends children who have walked at ten months and then some who have not walked until fifthteen months same with talking I have known some talking brilliantly before the age of two and others still struggling by the age of three and all have grown into normal children.I wouldnt say hes a big baby for 9 months. Im sure he was always on the lowest percentile as a tiny baby.
I do wonder how they ended up with such an adorable little boy though, hope they don't ruin him like Isla!