Has anyone ever had their kids recommended to a developmental specialist? If so what kind of things did they do with your child to evaluate them?

My son is just shy of 19 months old. He really only says a few words and doesnt comprehend anything that is said to him. He will respond to his name but if I was to ask him to get his ball or ask him where the book is, he has no idea what I'm talking about. He does not point nor look to see where I'm pointing to. His pediatrician says he seems to have problems with social interaction, where he is just kind of in his own little world.

He does not walk independently, he just recently started cruising along furniture. (He has little to no balance on his feet still.) I'm incredibly concerned and worried and just want to help my baby boy as much as possible 😞