assuming bisexual means in this context a biologically born man who is equally sexually attracted to gay men and straight women
Bisexual doesn’t mean that… Bisexual means someone who is attracted to two or more genders…
At least for me, it isn’t femboy
The OP explicitly said they’re attracted to femboys, so their experience is different to yours.
The only person who can say whether bisexual is the right label for the OP though is the OP. But if they feel it fits, it fits exactly the experience they’ve described.