What about his eye contact. Does he mixes up with other children. Was he saying some words before MMR vaccination ( 15 month ) and after that he stopped.
I hope and pray that there is nothing related to Autism INSHA ALLAH with your kid.
Just as precaution you can google for Autism checklist and have a go at it.
In case of any doubt just get him evaluated . Time is the key in such cases .
May Allah keep all children happy and healthy…