Buffy as a more serious, hardcore slayer (like Kendra)

Buffy is a slayer more like Kendra was. She had a female watcher who's killed. She was never allowed to talk to boys or wear makeup and always had to be serious and only focus on her calling. She had a crush on some boy once and got in trouble for trying to flirt with him or something, but I think he ends up being killed by vampires.

Spike helps her out after her watcher dies (can't remember why though bc I'm pretty sure he was soulless and didn't know her). They find out online (at a library I think?) that she was actually kidnapped by her watcher at a wedding and her parents have been looking her for her her whole life. Her watcher had told her that her parents gave her up to her. I think they do find her parents but she doesn't end up staying with them because its been so long and she doesn't feel like she fits in with them.

She and Spike have sex at some point (probably multiple time but I can't remember) and it's her first time.

That's literally all I can remember. Hope someone can help!

I just read this like 3 days ago after finding it browsing found fics.
It's called freedom by ice mink and I know is on ef.
Buffy had been captured by the master so no new slayers can be called and spike frees her. It's set in the wishverse. They go to library when spike tries to prove her female watcher tried to kill her to prove who she was and that the council had kidnapped her when she was a child. Spike vamps the watcher to get info instead of killing her outright (although he does stake her at the end mainly because Buffy hates her I think). Buffy gets turned into a vamp in this by her own choice as a way to help kill the master and also because of the councils behaviour and her own naïveté she doesn't feel like she belongs anywhere etc etc.
Good fic