My DS is 10 mo and not crawling. He has lots of time on the floor and can move himself round and sideways to get things, but not forwards. He ends up going backwards instead. All our baby friends are crawling/walking and I'm worries he's behind. It's only been the last couple of weeks that he's started sitting properly but I have to prop him initially, and then he's fine without support. Do I need to worry? He bears weight in his legs and can hold onto the furniture on his own but doesn't pull up.