6 months not rolling still

[OwlyLady]

DS is almost 6 months now and still isn't rolling over. His much younger baby friends are rolling over and some even showing signs of crawling. I've got the Wonder Weeks guide on baby's development and he seems to be rather behind on everything.
This seems strange to me as at 3 months he seemed to be slightly ahead on everything but from 4 months it's like he's stopped progressing.
Should I be worried or is there anything I can do to help him move on?

My 7 month DD still isn’t rolling either way! From talking to other mums, they are all so different. Apparently some babies never roll, just go straight to crawling!

Mine didn't till properly untill 8/9 months she's now ten and I think a few weeks away from walking. They're all so different. Ask your hv if your really worried.

Thank you. Reassuring to hear xx