Turning fanfiction into entirely my own work.

You may or may not remember that I wrote a Harry Potter fanfiction during NaNo called My Friend Is A Painting. I've started rewriting it as my own piece, set in my own world. I love the story and wanted to make it my own, since I only borrowed Hogwarts as the setting and the idea of ghosts in paintings. The painting doesn't contain a ghost anymore, though. It's just a painting that's alive, so to speak. I'm liking this version better and have found that quite a lot has changed. But can I still call it 'my own', since it originated as a fanfiction? What are your thoughts on this moral dilemma?

Here's Part 1 of the new version if you want to see: My Friend, The Painting (Part 1)

Honestly, inspiration comes from anywhere, and as long as you aren't using any of another writer's names, characters, or settings, you should be totally fine. Every writer borrows ideas from other books. You've put a lot of time and effort into your characters and world - regardless of where that inspiration came from, the story is definitely yours now.

Saw thisand here is my quick reply: 50 shades of gray...

Like @Mea said, inspiration comes from everywhere! If you just nab the inspiration and make all the other elements in your story your own, you should be just fine!