Am I really smart enough to be a doctor?

Some days-okay every day, but some days more than others- I really wonder if I am actually capable of being a physician. Mostly it's when I'm around other students. Or being asked questions. Or in any clinical situation whatsoever. My first two years of school it was easy to blow things off, and tell myself that I'd figure it all out and knowing all these tiny details wouldn't make me a better doctor. I told myself that test grades didn't determine my ability to be a good doctor. It was all about the clinical skills and knowledge that I'd gain over my third and fourth year. But as I reach the end of my third year, I feel like I don't actually know anything, still. My faith in my ability to be a doctor is severely decreasing every day. I can't answer questions that are asked of me, but I feel like all the other medical students are able to. I've heard that I don't really learn anything about medicine until I'm an intern and a resident, but somedays I feel that is just another way of allowing myself to live in denial about my inability to think well enough to be a doctor.
The first day of a new rotation is always the worst, but sometimes it doesn't get any better than that first day. Sometimes I just continue feeling like an idiot. I can't do anything right. I don't know anything. I'm terrified of everyone because I don't think I can make them better. I've already ruled out any profession where on a daily basis I am directly responsible for numerous life and death decisions (ie Emergency Medicine or Surgery) because I know I can't think on my feet the way I would need to in those situations. Maybe that is why I enjoyed outpatient pediatrics. I didn't have to save any lifes. Everyone was relatively healthy, even those who were sick. I didn't feel responsible for life or death decisions. But even in the outpatient world, there was plenty I had no clue about, so many things I didn't understand or know how to deal with, but I feel like I saw them a million times over and still can't figure them out.
So here I sit, three shifts into an emergency medicine rotation, watching physicians run codes and remember what they are supposed to do, and I can't even remember how to do a full neuro exam on a patient, or remember why I might need to. I can't answer a patient's questions about PAD or PID or UTIs or anything. I'm grossed out by half of the patients I see in the ED. I can't stand the noise, the smell, the shear number of people. It is too much for me. I don't like doing procedures. And it all stems from a feeling of inferiority and stupidity.
A doctor once told me that third year isn't really about learning how to be a doctor. It's about figuring out what you want to do and what you like, and learning how to learn. I don't think I've learned how to learn yet. I don't remember things I've already learned. I don't enjoy researching new things. I can't keep all the information in my head.
Another doctor told me the three things you need to be a good doctor are 1. a good personality so people will want to come see you (done), 2. efficiency (gots that) and 3. enough knowledge to function as a docto. That's the one I'm worried about. I liked him, because he said I didn't have to know everything about everything. I didn't have to have all the answers all the time. I didn't have to be a specialist in my field or any sort of genius. I just needed to know enough to deal with things as they came up, and know where to look when I didn't know the answers. That's the worry for me.
I used to want to be a specialist in some field. The fore-most knowledgeable person in whatever it is I choose to do. Now I just want to survive. I don't have enough faith in myself to think I'm going to be anything better than a mediocre doctor. I definitely will be depending more on my personailty than on my actual clinical knowledge. So I'd better work in a place where I don't need to know all that much, or I'm totally screwed.
Will I ever actually be a good doctor? The fact that I don't know much right now isn't an indication of my inability to ever know things right? I'll eventually learn won't I? Experience, practice makes perfect, all that good stuff? Seeing, doing, teaching, eventually knowing? I have to hold on to that hope or I won't be able to function any longer. I can barely function now as it is...