As others have said, this is very common. Over the next few months, your daughter's head will grow a lot and, if you give her tummy time and other time to not be laying on her head, it will more than likely even out. Our daughter had the same issue and, at 13 months, she's fine. We just made sure she had tummy time and slept on the other side of her head.
The biggest thing you should ask yourself is, do you trust your pediatrician? If not, you need to find one you can trust. You should be questioning everything they tell you. After all, they have seen hundreds, if not thousands, of children and they do have a degree.