How can I accept myself?

You don't except yourself because your afraid of what your family will say.The pressure made you break up with your girlfriend.Your the only person who knows yourself.Do you except yourself?Is your family biphobic?If you don't know ask them.If they are then your going to have to wait until
your 18.And you can't fight it.Bisexuality is there
FOREVER.It's not a
disease/disorder.It's not a choose.Nor is it a sin.Humans
and animals had it eons ago and have it now.Now about
your girlfriend.Did you love her?Get back together with her
if you did.Say sorry and explain why you broke up.She
could understand and get back together with you.She
might not want to.You can have other girlfriends or
boyfriends.There's plenty of people out there that may be
right for you. :)

It seems to me that you have already accepted yourself; you just want others to accept you. The only way to have this is to tell them about your sexuality. If you are ready for it, tell your family and friends and talk to them about it. Make sure you go at a pace you are comfortable with and sit and discuss the subject with whoever carefully in a way that you are happy with.