How do I write my book idea without infringing on copyright laws?

[Jenifer]

So over two years ago, I started writing a series of fan-fiction based off of a series I like. Now, two years later, the story has gotten sooooooo far away from the original source material, you really don't need to know anything about the series to read and understand the story I've written. The very beginning of it is in the same setting as the series and uses the same characters, but with a few name changes and location changes, it could potentially be unrecognizable.

So if I were to write this story and get it published, would it still be considered copyright infringement because its based on the series?

Sorry for posting this twice (one in Books & Authors, one in Law & Ethics) but I really appreciate your answers.