for the most part, i am attracted to girls. i strongly prefer them over guys almost exclusively. i say almost because i am honestly in love with a man. he's a lot older than me and it isn't a mutual thing, but i want to be romantically/sexually with him in a way that i don't really see myself with other men. would you consider me as being bi with a strong female preference or a lesbian with an exception?
That's happened to many people actually. You are whatever you consider yourself as. Remember, gay people have flexibility too!
It's possible that you're bisexual with a heavy preference for girls, but you could also be homoflexible (meaning you're basically homosexual but you can have an exception or two). But, I can't tell you your orientation. Only you can do that!