Is it something you are hoping to eventually puplish? IF SO then I highly recomind pulling it offline ASAP. You dont want to give people the opportunity to plagarize your work. In this situation I'd offer the story to a few TRUSTED reviewers who are willing to give you SERIOUS feedback. Not just "Its great. I love it!" But actual thoughts and constructive advice... mostly at this stage I'd worry about flow, plot, and creative input. You can worry about grammar and spelling at the next stage.
However, I warn you... if you pull one ofthe stories you are currently writing on dokuga, I might have to come after your with the "Rabid fan baton" and beat you with it, until you update!
If its something you want to post as an original fiction but not publish it... using a medium like livejournal, fictionpress, aff.com then in order to be SURE you have some helpful feedback on it, let your reviewers know that its being moved as an original fiction, and to which site. Give them a link, so they can go there read it and review it for you. OR you can always rework it as an original but keep doing the FANfiction one - unsing the fanfiction as the outline for the original fiction.
Its up to you how you wish to do it. I am warning you again though.... *pats her trusty Rabid Fan Baton* I'm watching.....