My almost-11-month-old son still crawls with his belly on the floor. He can get up on all fours when he is still, but doesn’t move forward or backward in that position. Also, though he can sit perfectly without support, he has not yet figured out how to get himself into a sitting position. He is able to pull to standing on his own and can get anywhere he wishes in a room. Are crawling on hands and knees, tummy off the floor, and getting himself to sit major milestones he is missing? Or is it okay at this point?
It sounds as though your son has accomplished some very nice gross motor skills. I wouldn’t panic at all. What I would do, though, is continue to put him on the floor on his belly and encourage him to get up on all fours.
Once he is on all fours, I would use a toy that motivates him and encourage him to move toward it. Also, each time you change his diaper, roll him to his side and encourage him to push himself up into the sitting position. Try hard not to put him on the floor to play in a sitting position; instead, put him on his belly or back so he has to either work on crawling or getting to sit on his own. If you do these few things, he should accomplish moving to sit and crawling in no time. If he still doesn’t seem to be gaining these skills, you can always discuss your concerns with your pediatrician.
Once he is on all fours, I would use a toy that motivates him and encourage him to move toward it. Also, each time you change his diaper, roll him to his side and encourage him to push himself up into the sitting position. Try hard not to put him on the floor to play in a sitting position; instead, put him on his belly or back so he has to either work on crawling or getting to sit on his own. If you do these few things, he should accomplish moving to sit and crawling in no time. If he still doesn’t seem to be gaining these skills, you can always discuss your concerns with your pediatrician.