When we went for my sons 9mo visit last month, we had to answer a bunch of questions on developmental milestones. There was one asking if he does "so big" or waves, which he didn't at the time.

Well he will be 10 months in a few days and still doesn't wave or do the "so big" thing. He also crawls but it's an army crawl type thing, not the conventional method.

And he can't get himself into a sitting position from crawling or laying down.

Should I be worried he is falling behind?

I should mention he was a month early so he normally hits milestones a little later but I want to make sure we are enabling him the best we can