my baby boy is 9 months old and he is 6kg,61cms height,41 cms head circumference...he doesn't crawl or sit on his own, he sits without support for few minutes when made to sit...what should I do?

A. See the crawling is seen between the age of nine months to 11 months so that is definitely not a problem but if your child is sitting independently when you make the child sit then it give it one more month and if you do not say happening on its own then you can check with your doctor