I believe that most people are inherently bisexual to some degree, and that sexuality is naturally fluid for women (maybe for men too, but I have doubts). I'd gotten to accept that it was constantly shifting about, so for me to finally settle in one place with it is a new thing. But now I know I'd be happier as a lesbian. The desire for men still exists, but I've gotten to where I can do without them. Women have so much more to offer. Men have only one thing. A very tempting thing at that... but on the whole... no thanks.
Analyzing why I felt drawn to men (apart from the sex itself), there were two additional reasons: 1) Protection and security on the street, 2) the general social pressure to conform to heteronormativity, because to be out gay is swimming against the current.
Both of these have changed: 1) I'm taking a women's self-defense class, and feel a lot more confident without a man to protect me, 2) I have firmed up inside me that I need to take a stand for lesbian sisterhood and solidarity, to support what I believe in, to resist heteronormativity. United we stand. There's more about why I am now so sure I'm lesbian, but it's private and I won't go into it here. But oh it's the most wonderful thing in the world! I feel like singing...