Worried mama of 8months old

My baby is 8months old and 1day. Im worried because his still little and seems brittle. he still cannot crawl,cannot sit without support. I also read here that that is one to worry about. And hes breathing seems fast like his exhausted . Where should i go? Nagchat po ako sa isang online pediatrician pero hindi daw po nya sakop yung ganung kaso general pediatrician daw po sya ang hanapin ko daw po Developmental pediatrician. Saan po kaya meron nun im around quezon city. Please help .any similar case po baka pwedeng malaman opinion nyo po and experience. 😢