What you are feeling sounds very normal, and I think nursing school does not really prepare you for feeling that way, even though I would say most of us went through the same thing. It takes a while to get your groove. Like others said, after about a year, you prob wont feel this way anymore, or at least it will be less often. You have to give it time. Make sure your having check ins with your manager and educator and tell them how your feeling. If they are any good they will validate you and tell you its ok. There were many times as a new grad I felt so overwhelmed I wanted to cry. You are literally still learning to be a nurse, even though you have graduated. Nursing school does not actually prepare you for the real world. Things take you longer because you are inexperienced. It just takes getting more experience unfortunately.
I just started a new job as an experienced nurse and even that was a bit overwhelming to me for the first few weeks. A whole new computer system, new staff, new doctors with their quirks etc. I was very frustrated for the first few weeks. It has gotten better. It will for you too.