I don't think the anatomy portion is that important for nursing school. Those anatomical points that are specific in nursing school are fairly straight forward and will not go nearly indepth as you did in your anatomy lab.
However, physiology is imperative for nursing school, especially for pathophysiology and pharmacology. If you do not understand the normal physiology in the body, it is pretty hard to understand the pathophysiology and how different drugs method of action work on the body.
That being said, I am betting you know a heck of a lot more A&P then you think. It is hard to comprehend that you learned that much, but I can guarantee you that when you start studying pathophysiology and the mechanisms of drugs on the body, you will begin to recall loads of information from A&P. I started nursing school only 2 months ago, and I took A&P Fall of 2005 and Spring of 2006 -- it was well over a year between A&P and nursing school and I can attest that I am having no troubles whatsoever.
Be confident in yourself and what you have learned -- don't doubt yourself so much.