My 7.5 month baby (corrected age 6month) born at 33weeks. He laughs when we make him laugh. He has decent eye contact and smiles a lot. He has also started turning head towards sound, but it is occasional. Sometimes he will not turn towards a loud sound but will turn head toward small sound like whistle. Also, he has little to no cooing and does not produce much sound either. We mentioned it to the doctor he has asked to wait till 9months corrected age. Please advise.