Should my baby girl be fully able to sit up by now? She will be 6 months on April 19th. She is able to sit forward with her hands on the ground in front of her holding herself up but she can't sit all the way up by herself yet. When she is leaning back on a pillow sitting up she starts sliding to the side because she can't quite hold herself up. I keep seeing everyone's baby pictures with them sitting up so it started to make me wonder if she should be able to sit up completely by now. Is what she does normal for 6 months?