Bisexuality Support Group
Bisexuality is a sexual orientation which refers to the aesthetic, romantic, and/or sexual attraction of individuals to other individuals of both their own and the opposite gender or sex. Most bisexuals are not equally attracted to men and women, and may even shift between states of finding either sex exclusively attractive over the course of time.
Sorry things have been confusing for you. It is possible to know you are bi without having been with both sexes. This link might help clear some stuff up for you, it helped me http://www.bisexualindex.org.uk/index.php/Bisexuality
hugs :)