My DS didn't sit on his own until about 6months. Apparently this is on the early side, but there is such a huge range. Some kids in my mum's group are 8months & only just rolling!! Every baby develops differently. You can help her by propping her up with cushions, etc to strengthen her back.
Most babies sit up on their own between 6 - 9 months so dont be too concerned her back will strengthen in time (tummy time helps with this too)gradually she will be able to sit up on her own longer but for the moment she will tumble over so all babies do stuff at their own pace grin
i wouldn't start thinking about that just yet - let her concentrate on rolling and tummy time (if she likes it lol! my DS hated it til 7 months).
my DS started sitting unsupported at 6 months 1 week. i helped him with it by sitting behind him with my legs out and him in between, so that if he fell back or sideways he would fall on me. as he got a bit more confident and better balance i then put a boomerang pillow behind him. after a few weeks he was very good at it and didn't need a pillow any more.
some babies can do it earlier than 6 months but majority is around 6 to 9 months. my DS had quite strong back and neck muscles and was sitting up straight on my lap from around 3 months, and around that time he started doing the "tummy crunch" movements when he was in his bouncer or car seat. all these things helped strengthen his back so if your DD is doing any of these things then she will probably sit unsupported earlier rather than later.
Yep. Don't rush it. I agree with lots of rolling and tummy time. Once she's up on her knees she'll learn to sit herself. Beware of 'plonking' a baby before they are ready. This can result in them bum shuffling instead of crawling. And, every baby is different. My 8 month old sat himself at 6.5 months after only a couple of weeks of rolling around and experimenting with pushing up on his legs. My 3 year old didn't sit himself until 10 months when I'd had enough and 'showed him the moves' one day. After that it clicked. Before that, he was happy rolling everywhere and only crawled for 2 weeks before he started cruising.
My son has only in the last week been able to sit unsupported for a good few minutes but i still have to keep an eye on him, he forgets sometimes and reaches for a toy to the side of him and topples over...and he's nearly 7.5 months old