How is this girl spying on me?

[Aimee]

A girl who is part of a facebook group I am a member of seems to be spying on me. I do not know her. We live in different countries. However, for the past few days she has been reposting pictures I post on my own facebook page - we are not friends - but not sharing them - just posting exactly the same ones shortly after I posted mine. I assumed my facebook account is not as private as I thought but now she is also posting quotes I post here under a different name and I know my YA account is private. I have never linked or told anyone on facebook my name here so cannot think how she found me or can see my posts?

[Ross]

I'd have to get in there, all guns blazing and have a very public argument with her, if possible with quotes or screenshots showing both of your posts

[Grant]

If you Google somebody's email address it will often come up with their other stuff (like their yahoo account). Honestly, I'd send her a nasty message then block her.