My 8 month old dd has been sitting up unsupported since before she was 5 months. But she has never got any further than this and she doesn't really bear much weight on her legs. She isn't showing any signs of crawling either. When I put her on her tummy she tends just to roll onto her back immediately. I tell myself that they are all different but I'm a bit worried about it. Should I be, or do you think she'll just develop in her own time and it's too early to be worrying?