I am just a nursing student (almost done though!), so I do not have a ton of "real life" experience for you, but here are my two cents.
Are you an introvert or just shy? I am kind of shy, but when I have a defined role in a situation I am very confidant and step up to the plate. If you do not like to talk to people or deal with people all day, I would say nursing is a big fat NO. You have to be able to communicate with your patients, patient's family, other nurses, doctors, housekeeping, respiratory therapy, pt, ot, etc... Sometimes you take 2 minutes to go pee and feel like it is the only alone time you have had the whole day where you have not had to talk to someone! Also, if the idea of asking someone when their last bowel movement was freaks you out... you may have an issue.
Okay, negative part over. I looooove nursing school (except the part where it is really hard and I am constantly stressed out). I love learning about the body systems and disease process and I find it all totally fascinating. I get what you say about doing things that produce tangible results, although sometimes those things are monitoring how much your patient is peeing each hour because they are on a drug that can mess with the kidneys. It is not glamorous, but for some people it is so "right." I worked as a CNA and sometimes I came home thinking that my life is one big blur of cleaning up poop, but the reward of knowing the difference that I made for my patients by treating them with dignity and kindness was always worth it.
There are so many different units and types of nursing that the possibilities seem endless. You can work in an ER, in an ICU/CCU, med/surg, home health, phone nurse for an insurance company, surgery, or about 100 other options. I dont think there is a one size fits all in nursing. You can usually work 8hr shifts or 12s. I knew people who did two 16s and an 8 fri-sun. OR or GI/Cath lab type jobs can do 6-2 mon-fri, on call once per month.
My dad is a nurse and he is totally amazing. His patients love him and it has provided a good living for 30 years. I think men can make awesome nurses. Only about 15% of my class are male, but I think the social stigma of only females being nurses is becoming a thing of the past.
I would say do research and find out what the job is really all about, then make your choice. There are accelerated programs if you already have a degree. No job is going to be perfect, but I think Nursing is very rewarding. Good luck on your journey!