I have been a nurse for almost two years now! Believe me we all been there. I remember my first few months driving home from work crying...thinking that i can't do it. Well....you can and you will! Try not to take criticism personally, but let it be a learning experience. In my opinion it takes at least a year to build up your confidence. I felt the same way about talking to doctor's and patient's family...but again confidence comes in time and if a family member asks you something that you are unsure of.....just tell them that you have to get back to them and look it up. You have to be an advoate for your patient...so it is important that you feel knowledgeable and comfortble talking with MD's. But again...this comes with time.
I was fortunate enough to work with a fanastic manager, who was always making sure I was on the right path of being successful. I work on a great unit, where 95% of us look out for each other and help each other out when the other is busy! Your work environment is very important!
Nursing school does not teach you everything. To this day, I still struggle with IV insertion, still have to look up things, I am not familiar with...but I am a better, more confident nurse today than I was when I started! Being a nurse you will learn new things all the time...no matter how many years you have under your belt! In my experience, it is a rewarding career with such diverse opportunities! Stick with it! Give yourself time! In a year from now you will look back and see how far you had come! Good luck!