I do however harbor a certain dislike for the third gender.
There are men and women and you are somewhere on that sliding scale.
Jut make your pick and stop telling people to refer to you as "they" or whatever pronouns tumblr invented.
There is a sliding scale for sexuality (indeed, one can slide along it). But this isn't even the same as the scale for sex (bodily composition
1, as a mix of phenotype, chemistry and DNA, or best guess where they mismatch) or gender (what the mind thinks
2, perhaps the least measurable or confirmable comparison, but heartfelt by the individual nonetheless).
A simplified way to remember: gender is what's between your ears; sex is what's between your legs; sexuality is
who's between your legs.
1 Ambiguous genitalia exist, and may be considered 'fixed' at birth except for hormonal 'revelations or surgical intervention. (In recent times, infants have been altered by well-meaning doctors, but I think "wait and see what they want for themselves" has been a growing policy, aside from anything necessary for actual congenital problems.)
2 Very fluid. As in the fluidity itself is a fluid thing. Hard to know how much people are 'persuaded' to adopt their physical sex as their gender, like they may have been asked to 'play' the heterosexual despite their actual tendencies, but
examples exist to show that mind/body mismatches are possible, even with the full force of nurture behind the physical side.