People needn't be either wholly straight or wholly gay, and most people aren't. It's a conventional over-simplification to insist otherwise. Some have a weak sense of themselves, and will try to bolster their confidence by forcing you onto their "side." You shouldn't need others to tell you who you are or to approve of you. Many psychologists recognize a scale of sexual orientation, with exclusive hetero- or homosexuality at the extremes. See this link for an example:
http://www.samabhavana.org/kline_scale.html
The problem is that sexuality is considered an essential matter by religions, by cultures, and more recently by political movements. Regardless of who you are or how you act, someone with an agenda will have an opinion about you. I would give you three pieces of advice:
First, do as you please. So long as you do no one harm and your life adds to the community, it is pointless to concern yourself with whether your innermost feelings match some official version. That version may be lived by surprisingly few people. Remember that no one can see what you feel, only what you say or do. In other words, sex, while social, is not public. No one really knows what normal sex is because the unvarnished data is simply unavailable. Sex is terra incognita. So don't worry about who you're "supposed" to be, because even the guardians of the official version may not stick to it themselves. Follow your heart. This will make you happy, and probably those close to you. Let the lies you've built to conform slip away.
Second, be discreet. I know this will enrage many who have politicized sex, but you are not obligated to be a martyr for anyone's cause. Just conduct your sexual life as you please, never lie, but don't provoke confrontations. If you want to kiss and hold your boyfriend's butt in public - do it! Just understand how others may react, and choose according to what you most value. You have to act based on an honest assessment of the world you live in, not the way things "should" be.
Third, become the sort of person who doesn't give a damn what most people think. I don't mean you should be reckless or uncaring. I mean that you needn't be a prisoner of other's values, especially values whose only purpose is to conform. Your values, founded on the unbudgeable reality of your life, are equally legitimate. You are the example that proves what a good thing it is to be someone like you. I understand that millions of people, especially in the U.S., where the ordinary is celebrated by our market culture, seek to be as much like others as possible. If you think this way, it will be hard to be gay or bisexual, because your ambition in life is to be just another cow lowing in the herd. Common people, knowing themselves to be common, seek to elevate the common. But there is another mindset, one that strives for excellence, one that seeks to distinguish itself, one that is arrogant, elitist, and not a little snobbish. If you think this way, it will be much easier to be gay or bisexual, because your ambition in life will be to separate yourself from the herd. Extraordinary people, knowing themselves to be extraordinary, seek to elevate themselves. Cultivate things in yourself to be proud of, and damn the rabble. You may be surprised to find that confidence converts. People will respect you if you respect yourself. Don't cultivate "gay pride." It's as silly to be proud of being gay as it is to be proud of being straight. One's sexuality is a generic characteristic, like hair color. Cultivate Kasper pride and you'll do well.
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