Im having dreams about this girl who has interest me a lot because she is from a different country and really nice Iam a girl and straight I'm not even in the girls class anymore?

There is nothing unusual or problematic in dreaming about people or things that interest you. Dreams are not limited to romantic or sexual matters, and they really have nothing to do with being gay or straight. Even when dreams include sexual behavior, the underlying meaning can be completely different, such as getting in touch with a neglected part of yourself or finding new modes of expression, or simply illustrating great joy or excitement.