I highly doubt that the way she scoots has anything to do with her spine development. At your next pediatrician appointment have the doctor take a look. She could have scoliosis, which is a curvature of the spine.
I know plenty of babies that scooted on their butt, or crawled with their elbows or one knee and one hand and it did not cause any developmental issues. So most likely this is just the way she is developing.
Just an FYI, I have mild scoliosis and it never effected me. My doctors took a wait and see approach if it had progressed I would have needed to wear a brace, but I never needed to.
I suggest let her walk at her own pace and check with your pediatrician!