Ferdie, I don't think your OB was trying to say that you would be a bad anesthesiologist, but she made a good point about the fact that it is uniquely stressful. The attendings and residents that I know who enjoy anesthesiology the most are those that NEVER freak out. You could tell them anything, or throw them into any situation, and they would respond calmly.
I know plenty of anesthesiologists who freak out constantly, and it seems like their working lives are pretty unpleasant. They often are great at what they do, but it seems to take a big toll on them personally.
Imagine this: if you were the only person at your first code, would you be thinking "awesome!" as you automatically reached for the head to put the pt in sniffing position? (in a pt with no possibility of C-spine trauma, of course)
Or, would you be thinking "oh my g-d, I've never done this before on a real patient, I don't know what to do, where the hell is everyone".
In anesthesia, there are CONSTANTLY situations where it appears that the patient will die immediately without your intervention. Often, you have to decide VERY quickly how you are going to intervene based on many options and limited information. The question is, do you enjoy this kind of stress, or would it drive you nuts?