My daughter was a little behind when she was your daughter's age, the pediatrician said she was within normal range. However, she ended up having learning disabilities, which was very difficult for her. She has worked hard to raise her IQ 20 points, and is doing very well in college, but it hurt her self-esteem. When she was finally evaluated in 6th grade (because I kept looking for answers), I was told she was a classic case. I say all this because I as the parent felt there was a delay, while the pros said no, until she was very far behind. Good for you for speaking up and looking for answers.
What you are looking for is validation that she is a little developmentally delayed. She probably needs to do some good old fashioned baby-work to develop. Today, moms are afraid to put the baby on their stomach to play, because they might get SIDS. Moms are afraid to put them on their back to play because they might throw up and choke and die. But bablies MUST play on their backs and fronts as much as possible to develop normally, not just physically but also neurologically. For example, playing on the back develops their senses, and powers of concentration and memory. Playing ont he front develops back and neck muscles needed to roll over and sit up. So put her on the floor, sing to her, rattle things for her, show her pictures, let her grab, play peek-a-boo - all on the floor.
If she is still showing signs of being easily startled after 9 months, contact an occupational therapist for a primitive reflex evaluation. These reflexes need to be integrated by then, and an OT who is trained in this can not only evaluate her, but can show you exercises to help her catch up.
If you want any more information, feel free to contact me privately; I work with older children who have ADD/ADHD, LD, Dyslexia, etc, and all have had some of the primitive reflexes that were not well integrated.
Best of luck from someone who has been there :)
K. Johnson, MS Ed