We are thinking of getting a booster seat for our DS who is 2.6 and weighs 2 1/2 stone. He is perfectly in proportion by the way and looks amazing, I am told he is more the size of a 4 year old though. He seems a little big for his forward facing car seat. I dont know what the regulations are for this age range & size though. Can you enlighten me? Would a booster be better for him? Thanks!