I have been RN for 33 years. The confidence part of the job comes with time. It took me about a year after graduating to feel really confident in my work. That is true with many jobs. That first year was rough but I am glad I hung in there because I have really loved being a nurse. One of my main fears is that I would make a mistake that would seriously hurt or kill someone. Of course, that has never happened.
Kaliope has some good techniques for relaxation. Keep your goal of graduation and getting that diploma in the forefront of your mind. You have gotten this far so obviously you can do the work. You can PM me if you need some support.