I went through something like the process you describe when I thought I wanted to be a CPA. I finally realized I not only didn't want to be a CPA, I didn't even want to work in accounting, I just enjoyed doing accounting problems, because they were "word problems" and I'm good at those and enjoy them (enjoy algebra word problems, computer programming, writing papers, etc.).

Maybe look at what part of "nursing" you think you enjoy/are good at and relate that to the actual/whole of nursing? There are many ways to "help" and there can be many subjects we like to think about intellectually but that does not mean that the helping and the intellectual subjects need to go together? People are not just body parts, like A&P studies it, as a matter of fact, that's the least of what they are? You may want to do research or teach or something else entirely, instead.