Do you suffer from "Good Patient Syndrome"?? Do you have a tendency to do what the doctor says, even when it goes against your instincts, even when you've promised yourself you'd be a stronger self-advocate?
I just ran across a wonderful article on the International Caesarean Awareness Network (ICAN)'s website, which discusses using Emotional Freedom Technique (EFT) to enable oneself to be more assertive when communicating with "authority figures", specifically medical staff during birth. While it is, of course, very important to maintain communication in as amicable a manner as possible, it doesn't mean that you need to allow your rights to be trampled on, especially during a rite of passage as important to both you and your baby as your baby's birth.
Here is the article
Read. Absorb. Allow yourself to become empowered . . . in the end, noone can really speak up for you but you. Good luck on your journey and peace in birth!