Bisexuality is a curious issue to me... I consider myself bisexual, but I think that there are different levels of it and that it varies.
My progression was something along the lines of... I was mostly indifferent early on, but I'd never been interested in guys. I met my best friend, a girl, in first grade. Another friend, who was a guy, I met a bit later. Now I mostly have friends who are girls. I used to think that there was a pattern in that guys who hung out with mostly girls at an early age would more likely be gay, and the same for girls who had mostly guy friends. Maybe there is, with some exceptions.
In late elementary school, there was one girl I was interested in, but I never talked to her, just because I was the quiet, shy type. In Junior High, I wasn't interested in anybody. Never even considered it. In early High School, I dated a few girls, but the relationships never lasted long, and I was usually very indifferent towards them in the relationship... I never felt anything passionate towards them.
In fact, even now, I consider myself to never have loved someone before [outside of the "kin"-type love you have with close friends and family].
Around a year - half a year ago I decided to come out bisexual. There are a lot of guys and girls who constantly catch my eyes when I see them in hallways or in class. I've never dated another guy though... it's difficult to imagine myself in a relationship with one, even though I usually find guys more attractive in general. I've still never been in a seriously relationship with anyone though, so I'm thinking I need to initiate a relationship before I find out where I'd like to lean. I just don't know right now.
Like someone above had said, bisexuality isn't looking to have both sexes... I find polygamy [and, well, sex and porn in general] revolting. I just want one person... I don't explicitly care whether that person is male or female.
Sorry for multiple jumbled thoughts in one unorganized post.