R.P.
My DD who is now 10months finally rolled at 9.5 months. The doc wasn't to concerned each time I brought the subject up at doctor appointments. She sat up by herself at 5.5months and was scooting around on the floor by 6.5 months. Each child is different. Here is when I learned this, in late Aug we had a family reunion and there were three babies, a 8month old my dd at 8.5 and a 9month old. The 8month old was walking with help with no teeth and not saying any words, my dd that sat up early and scooted and had 6 teeth and didn't even want to stand with help yet and the 9month old was like a monkey crawling on everything climbing on anyone to anything in reach but like baby 1 not talking with no teeth. Each child is different and will grow into different stages at different times. My daughter now says three words, rolls only form back to tummy with rare occasions tummy to back, scoots everywhere she wants and walks all over with help.
Hope this helps ease your mind!