Don't worry. My son will be eleven months old on the 22nd and is doing really well, but he didn't roll over until he was 6 1/2 months old. Like you, I was starting to get worried, but his doctor said not to worry. All kids develop at their own pace. My son also hated to be placed on his stomach and I thought that was why he would not roll over. I just started putting him on his stomach for a few minutes each day and just let him be mad. One day he was throwing a fit about being on his stomach and just flipped over. He was so suprised. After that first time I could put him on his belly and he would roll right over, but he was close to 8 months before he would roll from his back to his stomach. Now he rolls all over the place, and crawls, and pulls up on things just like any other kid his age.