I don't really see how dressing up as a character you made up is disrespectful. oUo; I don't see how even fan-characters are disrespectful. You're still a fan of the series, what harm is there? Imitation is a form of flattery, after all.
And I don't see the point in changing your mind to an existing character... Though you should ask yourself; Are you cosplaying for yourself? Or are you just doing it for attention? Or maybe you're doing it to please other people?
Wear what you want to wear, not for what others are going to think, or not to be more popular :/
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Though really, if you want any attention being an OC, as Nikki said, there should be some defining characteristics, so that you don't just look like someone who just was too lazy to get a cosplay. (by that I mean, someone in a T-shirt and a naruto headband claiming they're an OC)
I really like your outfit idea, though if you try to pass it off as 'another Org member', you might get many murmurs or accusations of being a Mary Sue :'D Maybe not to your face, but...