Encouragement please.

Can anyone share encouragement as I feel extremely discouraged. I know I should not compare but the differences between my older two and my 10mo are so stark.

My almost 10mo still doesn’t say any words (dada, mama, ect), or even babble. He just kind of yells, if he makes any noises at all. It’s like “ahhhhhh”, with very little inflection change. For the most part, he doesn’t make any sounds. I sing him to him all day and narrate everything I am doing. He will look at you if you say his name sometimes but not consistently. He doesn’t want to play with anyone, never cuddles, or wants to be held. I read him ten books every day but he hates it and just throws himself backwards to get away. He just wants to be left alone honestly. He won’t really repeat anything. He doesn’t clap or shake his head. Every so often, he will copy hitting two blocks together.

In public, he’s extremely stoic. He will just stare at everyone. If strangers try to talk to him, he will scream or stare at them with a dead expression.

He can definitely hear and his vision doesn’t seem to be an issue. He meets his gross milestones just as I start to get concerned (like the very tail end of normal ranges). He is army crawling and trying to pull to stand.

Due to insurance changes, his 9mo check up is next week and I plan to bring it up. Is there anything else I can do to encourage babbling or being social? Any other babies out there that sounded similar that suddenly perked up socially and started talking/babbling?