Not necessarily. Bisexuality can sometimes be transient in some individuals who are questioning their sexual orientation, although not everyone who questions their sexual orientation is bisexual.
Studies have shown that exclusive homosexuality and heterosexuality are two poles between which human sexuality and bisexuality can be expressed. In other words, there are infinite forms of bisexuality that can be placed on a scale ranging from “exclusively heterosexual” to “exclusively homosexual”.
Source: Ministère de la Santé et des Services sociaux in collaboration with the CLSC des Faubourgs in Montréal, Bien vivre son orientation sexuelle – Les femmes et l’homosexualité, 1999, page 7.