As Holmbo says, I guess that the best option would be to see a therapist. If you are a minor, you should try to tell your parents about it, if it is save for you, and maybe set an appointment with an expert. If you are not able to talk to them because of x or y reasons, does your school have an orientator (I don't know if it is called this way, in my school we call the specialist in mind this way...)? If it does, you could try to talk to them about the way you feel (or don't feel).
Sexuality is fluid, and it can change during lifetime, depending on the situations. As a personal experience, my way to describe my identity has changed like twenty times. I started like a cisgender female bisexual and in six years I went through labels like lesbian, pan, bi again, pan again, bigender, intergender, genderfluid, ace, gray-ace... And more. And I felt confident in those all. With this I want to say that labels are a way to describe ourselves in a determinate moment of our life. Ones might want to label themselves, others don't. If bisexual was a label that once fit you, then everything is alright, it accomplished it's will, but if you feel that this label does't fit you anymore, there is no rush to find another that does, if you want to change it.