Hey honey, I'm the same age as you and I'm thinking I'm bi. I will hereby give you a hug, *hugs*.
My advice is to come out when you're ready.You don't have to come out as soon as you accept your bisexuality as your orientation.
I know homophobic parents can be frustrating, but if you're kind, act mature, and be respectful when you come out to them, it'll be a good thing. I'm not saying they'll accept your orientation, but being mature is a good thing when it comes to having serious discussions with your parents.
Honeeeyyyy I'm 16 and in the same situation as well. I'm a girl and my parents think I'm as straight as can be. All of my friends know I'm bi but I'm thinking about waiting till I'm 18 to tell my family. If you think you might be in any danger as a result of coming out, or if you think your parents will refuse to support you, wait until you're 18 or until you have a decent job, whichever comes first. Safety first, sweetie!