this is a common issue that most indian moms face, as almost everyone, except your baby's doc, will be unhappy or worried about your baby's weight!
as per the weight indicators, at age 1, your baby should weigh 3 times the birth weight, which, in your baby's case, should have been 6 kg, and the fact that your baby is 8.5 kg means that the weight is good :) you can also check the same with your baby's doc and see whether the weight is as it should be.
as for those worried souls, next time they have a problem, tell them the doc is happy with your baby's weight, and next time you'd love them to come along to ease their concerns ;)
Debolina Raja