It takes a lot of courage to write about your feelings and your sexuality and to try and find answers to them. It is important to tell you that these feelings you're describing are natural; people of all ages and genders go through stages of questioning their sexuality. It sounds like you are confused and need some help sorting your feelings out, and that's okay.
It might help for you to look at sexual orientation as involving emotional, romantic and physical feelings and attraction for people of both genders (bisexual), people of the same gender (lesbian and gay), and people of the opposite gender (heterosexual or straight). It might also help to think about who you have crushes on, girls or boys or both. Bisexuality is a normal expression of human sexuality. Embrace your feelings and realize that this is a journey of discovery; it may take you a while to sort through your feelings. You are young, so don't feel like you need to figure this out all at once.
There are many resources for you to look at as you try to find answers. On www.bisexual.org you'll find helpful information on bisexuality. Click on Resources then Bisexuality-General Information to find information that may help. I also encourage you to check out www.trevorspace.org. This is the Trevor Project's online social network for LGBTQ youth ages 13-24. This is a safe space for you to connect with other young people with similar questions and find a supportive network of peers. Above all, you'll find that you're not alone, and that there are people you can reach out to for support.