Congratulations on your scholarship- that opens a lot of doors and options for you! Secondly, good job on thinking about this carefully- as a bio major, I knew a lot of pre-meds who didn't really think about what being a doctor meant.
Straight facts first: The usual path to becoming a doctor is 4 years of college, 4 years of medical school, and at least 4 years of post-MD training (1 year internship, 3 - 6 years of residency depending on your specialty). It doesn't matter if you're going into general practice or brain surgery, those years are pretty much required. Dentists go through something similar (4 years of college, 4 years of dental school, and then some post-doctoral training if you want to specialize in a harder field like orthodontics or pediatric denistry) but it's a different school.
(You don't need a master's degree to become a doctor or dentist. However, a master's degree or something like it is usually required to become a nurse, dental hygienist, medical technician, medical administrator, etc.)
That's a lot of years of school, and you're right to be cautious before committing to it. The good news is that you don't have to decide right now. What I suggest is to talk to your high school's career office or the local hospital and see if you can volunteer at a hospital or talk to a doctor about what the job is really like. You may find that this is what you really want to do, or you may find that you can't stand the sight of blood.
If you can see the job being done and decide it's for you, then the years of school will be ok because it gets you to your goal. If not, then keep on looking for jobs that do suit you, and work towards that. :)