my baby is nearly 6 months but in 9-12month old clothes..he was big at birth!!! and is fast growing out of his baby car seat..his head is to the top of the seat and ive puit him in another model that seems a bit roomier ..he can sit up and is very strong..can he go forward facing yet as hes over 9kg and the forward ones say from 9 kg upwards but do you think its better to leave him be or move him