IIRC, she's still planning on ending the actual main story at 12, but there are side stories/volumes/etc. At least, that's the last I heard. If there's some new info, please link where you found it. I'd love to know, too, b/c it'd be great.
Sociopath? Lol. Read this maybe it’ll elucidate you about the characters.
To answer your LN question Shima does fall in love with Adachi, she even says so. In death, Shima chose to stay with Adachi in the afterlife over Gon and her grandparents if that tells you anything.