As I understand it, bisexual is more about the gender binary, that is to say "male" or "female" and what you've described is typically the definition of pansexuality, but pansexuality is relatively new as a label and there is no obligation to use it. If you feel happier describing yourself as bisexual, I don't suppose there are any who would tell you different. In essence, I guess if a person is pansexual, they are still bisexual too, just with added extra?