My baby is 8 months old and I'm getting nervous. She is not crawling or even trying to crawl. she just rolls all over thr place. When she rolls she doesn't bends her knees either. she sits perfect since 5 months. Idk what can I so to guide her to stand or bend her knees. We go to a mommy and me group and I see all the babies her age or even yunger at least bending their knees When they r on their tummy.