It's so hard not to compare. DS1 (now almost aged 4) was crawling and pulling himself up to stand at this point. DS2 (9 months old) is showing zero signs of wanting to crawl.
He sits and brings his body forward when he tries to reach something.
When I lay him on his tummy, he doesn't even try and bear weight on his arms, he just rolls back onto his back.
Meeting all other milestones fine. Are some babies just not crawlers?!!