D.M.
A.,
I think it's interesting that the opinion came from an instructor. Was this instructor a previous patient, know patients and, did she base her opinion on facts or heresay?
I feel very strongly about my OBGYN and LOVE her for how she has cared for me while pregnant and then after. Speaking from experience, when you've chosen the wrong doctor you will know. My OBGYN took me on after I left a group of doctor's who had varying ideologies about birthing and when I found out the ONE doctor I thought I was going to see might not even be on-call the night I gave birth.
At any rate, I wouldn't switch doctors just yet. At your next appointment talk to her about your birthing plan, and how you wish to approach things. See how she feels and what her opinion is, and then go from there.
Based on one person's opinion it is tough to make a judgement about someone. However, I understand your desire to do it your way and wish I had gotten the chance. Just make sure you know understand that everything changes in a split second and your birthing plan may have to be thrown out the window...for the safety of you and your baby.
Mine was 8 weeks early for no good medical reason, and that was just that.
I would get a doula who can help you while you are there and be your birthing advocate. Have her help you through this process...really the tough part is talking to the nurses and having someone to make sure they hear you and your needs!!
Good Luck, and congrats on the baby!