Not babbling at nearly 9 months

Needing to know this can be normal or if this has happened with anyone else’s kids.

My son will be 9 months on the 24th and does not babble. Every once in a while we’ll get a “mmmma” or “ga” and sometimes a na when he’s upset. It’s usually when he’s frustrated we get this. It’s few and far between. He’s also a big baby who isn’t crawling or getting himself to sitting yet. We have a prescription for PT starting next week, and are starting SLP in July.

I just want to hear from other parents whose kids didn’t babble til later and went on to be developmentally typical. I have family trauma around this and it’s hard that everyone I know has 4-6 month olds babbling mamamama dadada bababa etc.