Not sure I should stay at my first job as a new grad RN, will working nights help me?

OK, so I am currently in orientation (just finished my 9th week) on a Neuro ICU as a new grad RN. The last couple of weeks have been extremely rough for me. I have been feeling extremely overwhelmed every day I work for the entire 12+ hr shift and do not feeling happy or enjoying my job whatsoever. My skills are still not up to speed and I still struggle with time management because of this as well as prioritization. Most days I feel like all my instincts are all wrong and am very frustrated with myself and question if I am competent enough to do this job. I am afraid that I am going to develop an ulcer from the immense stress I am feeling or that something worse will happen. Most days I go 7-8 hrs into my shift before I can use the bathroon or take a break and eat something. I have been feeling very depressed lately and even broke down crying when talking with my preceptor about how I think I am doing after the last shift we worked together. I am starting to wonder if I am feeling this way simply because I am new and the first year of being a nurse completely sucks or because this unit is not the right fit for me. I have wanted to work in criticalk care ever since I worked as a tech in a general ICU while I was in nursing school, I absolutely loved the environment. I have been working day shift so far in my orientation and am going to be transitioning to night shift next week. My preceptor thinks that I will do well on night shift as there are less interruptions, traveling with the pt, etc. I am hoping that this is the case but, overall I am still on the fence about this unit and if I should stay. I have even spoken with my boss the other day about what I am experiencing and she (like everyone else) tells me that it is apparently normal to be a depressed nervous wreck as a new nurse. She also thinks nights will help me become more comfortable. My boss is extremely supportive and said that she would help me find another unit to work in, if it comes down to that. I am just very upset about this whole situation and am feeling like a complete failure because I am not coping well with any of this. I don't want to be a quitter but, I don't want to be at a job that makes me miserable and I hate. I have decided to not give up just yet and work the next week on the night shift and see how it goes. I guess I am just afraid of still feeling the way I do even on nights...then what do I do? I am not sure where to go from this unit if I decide this isn't for me. Anyone out there feel like me and then switch to the night shift and it got better?? I am not too thrilled about working nights but, if it helps me deal with this job and adjust then I would be more than willing to work these hours. Any thoughts on this are much appreciated and thanks for letting me vent.