finally writing this out..advice what do you think

[dfiant]

how can someone like one sex for this long then like another sex years later?

Commonly referred to as 'Latent (Dormant) sexuality'

when I was 5 once or twice i dressed up like s girl

A bad stereotype. Believe it or not, 99% of gay males have never, will never or even had a desire to wear girls clothes.

as time went on at the age of 15 my dad would tell everyone I was gay which confused people and I would get so pissed

Enough to repress your sexuality I would imagine.

not "back door" sex that doesn't * turn me on at all

Once again, a bad stereotype. Anal sex doesn't define a man as a gay man and not liking anal doesn't make him any less of a gayman.

do people really have a gaydar?

Yes

has misconceptions about gay men I've always thought

Yes

I'm not sure what to do or think about this what am I?

A human that is trying to label himself instead of just being himself. Labels are for clothes, stereotypes are for small minded people who have no grasp on reality.

is being bi a coop out don't I have to choose which sex I like?

No choice in the matter, your either like or you don't like...simple as that and you are over thinking everything.