tsmallz --
I would suggest at your stage of the game that you just focus on medicine as a grand picture, and leave the specialty details as something to be worked out later. Of course there are some folks who 'know' before they start exactly what they want to do, but the majority of them end up changing their minds along the way. I just knew I was going to do orthopaedics, for example, but switched to neurosurgery when I decided that ortho -- for me -- would be about as exciting as putting together a desk several times a day for the rest of my life.
Regarding radiology, though, vegard the viking already summed it up fairly well -- great pay, flexible hours, and as much or as little call as you want. Unfortunately the thing about radiology that's so great -- the ability to do the job from anywhere, at any time, via computer -- is the same thing that makes it risky. Even if humans always continue to read films (and not some computer algorithm) the chance remains that film reading could become commoditized such that it's performed by the lowest qualified bidder anywhere in the world. It's already started to happen to a small extent, as Massachusetts General Hospital (a/w Harvard) several years ago began farming out some of their films to 'subcontractors' in India. Such developments make me fear for the job security of American radiologists in the future. Also, interventional radiology is a field pioneered by the radiologists, but which is being taken over gradually by surgeons. Vascular surgery and neurosurgery have made inroads into the most profitable interventional radiology procedures, and the trend seems likely to continue b/c surgeons will always control the referral base.
Anyhow, these are details you can learn about later. For now, just focus on doing well in college. Go to the best school you can (it matters for med school admissions -- I had a difficult time getting admitted out of a state school despite a 4.0 GPA and a 37 on the MCAT) and do well in classes. However, DO NOT shut yourself in your room and study all the time; the college years are unique, and not to be missed. Enjoy yourself, run hard and run a lot, and don't leave with any regrets.
Oh, and as for the OCD thing and surgery -- I used to be the same way. When I was in high school I used to have nightmares about contracting HIV from a syringe that somebody had poked up through the cushion of a theater seat. The funny thing is, you might just get over it. I've been stuck twice with needles while in school, and I've taken the antiviral prophylaxis as I was supposed to do, and lo and behold I'm fine. The fact is that if you're careful about things, occupational exposures are EXCEEDINGLY unlikely to result in the contraction of any serious illnesses -- especially since the advent and widespread employment of the Hepatitis B vaccine. So don't worry about it! And good luck.