Job hunting

I always wonder why I have very low confident at all times. Am I lack of some kind of nutrition that I'm not aware of? Am I born without it? 

After I heard that I would be compared with RN "S" and RN "M" during the interview. I started feeling freaked out. It makes me insomnia. When I started thinking what I could become better candidate than the other two, I... Couldn't think of any. I meant I know that I have passion. My colleagues admire me with hard working, then I earned an inspired care award. I determined to become a deputy manager as my long term goal; therefore I would like to work in high care facility to enhance my knowledge and explore my experience. However, I can't stop thinking how good RN "S" is. Im also afraid that RN "M" will earn the job position as she is the junior among all candidates.