9 almost 10 month old not standing

So my son is about a week away from being 10 months old and he’s still having a hard time standing. If we hold him up on his feet he stands with his butt out but doesn’t stand up straight and really put weight on his legs.

Should I be worried?

He IS crawling. He knows how to hold himself on his hands and knees but when he crawls he chooses to army crawl on his stomach using his elbows.

The doctor seemed concerned at his 9 month appointment about his standing so that’s why I’m here asking if anyone else’s baby did any of this and did it end up being ok? I’m hoping he’s just learning a bit slower then other babies and that nothing is wrong.