Thanks for your responses everyone.

To those of you who think I'm a tomboy because I'm attracted to men:
This is a bit personal, but when you fantasize (sexually) do you picture yourself as a man or a woman? I always picture myself as a man. I could be a tomboy, but my craving and strong desire to actually be a guy makes me think otherwise. I'm not happy as I currently am, but I would be more than happy and comfortable having a male body. The way I see it, I never thought about it when I was younger because I was just used to what I had, but as soon as the idea was planted in my head I realised I wasn't happy physically being a girl.

I heard somewhere that "who you want to go to bed as, and who you want to sleep with, are two different things" so I don't think my sexual tastes should even factor into it, because I want to go to bed as a man. Also, I'm not straight, I'm bisexual, I just happen to think men are amazing/I'd love to be one, so I find myself more interested in them over women.

To everyone else:
I have a pretty good idea how my family would react. My aunt came out as a lesbian a few years ago, and she dresses herself in a male way, and everyone in my family (except for my sister/best friend) constantly makes nasty remarks about her and treats her like she's an alien. I'm mostly worried about my dad, because he's really unaccepting, and he's also old and has epilepsy, so he'll be needing someone to take care of him, which is going to be me, and I don't want to push him closer to the grave by doing something selfish like transitioning to a guy, because I know it would have a major impact on his life and his relationship with me (even though he already treats me like I'm his son, but he'd freak if I decided to actually to be his son).

Basically it comes down to: should I be selfish and ruin the few relationships I have in my life, or not?

I was considering dressing up as a guy temporarily to see how they reacted to it, and if it was negative then I wouldn't continue.