RN lacking confidence and assertiveness

Hi everyone! So I just passed my one year mark of being an RN, and although I feel as though I have made progress, and am getting into the groove of things, I feel like I am still lacking a lot of nurse qualities. My first nine months I worked in a LTC facility caring for up to 30 patients... it was very overwhelming, hard to learn in a setting like this, I received little to no support from colleagues, and it was just overall not a good experience. I left and am currently at a sub-acute rehab facility. I like it there much better, but am still having a lot of doubt and anxiety about my abilities as a nurse. Tomorrow is my first day off orientation, and I will be on my own. I am very comfortable with passing medications, administering treatments, putting in orders, and the basic skills that nurses do. What I have severe/crazy anxiety about is critical thinking, communicating with doctors and NPs, expressing concerns with them, and fearing they will ask me questions and I'll look at them dumbfounded. Don't get me wrong, a lot of the doctors who work at my facility, are very welcoming and easy to approach, but I still get scared. I know that the more I put myself in scary, uncomfortable situations, the faster I will get used to it, and become more confident in doing it. Yes I know people say critical thinking takes time, but I feel as though I should SOMEWHAT feel a bit more comfortable talking to doctors, etc. I am afraid to sound and look like an idiot, and I feel as though I literally know nothing related to nursing. I am so consumed with my busy, daily tasks, that I may easily overlook important things. I am usually able to determine if something is wrong with my patient, but it's the actions after that, that I freeze up with. What is causing the problem? What warrants a call to the doctor? Am I overreacting over something that isn't important? My mind goes into overdrive. This is one of my biggest struggles. I'm hoping as I get more and more experience under my belt, I will become more comfortable, but it's a serious lack of self-esteem that is bringing me down, and doubting my abilities. Some days I tell myself I am not cut out to be a nurse, which makes me even more upset because I know I am capable.  Does anyone have any advice for me? People say fake it until you make it, but it's easier said than done!