Baby doesn't reach out

It could be because she was a preemie. Has her size adjusted to her chronological age? When looking at the development of a baby who was born prematurely, their development is calibrated from their due date - not their actual birth date- so if your baby was born eight weeks early - you'd expect them to be hitting the developmental milestones of a child two months younger.

So at the adjusted age of eight months- I'd be concerned that my child was not reaching out for toys.
In terms of sitting up - is she a big girl - or is she still tiny for her age? How's her muscle development and head control?
I wouldn't be concerned about the lack of crawling yet.

What does your pediatrician say? Surely s/he's following the baby's development.