I love how you think you created something completely awful, but then it turns out to be awesome. That's what happened with my fanfic character, Nareta (from my second Pokémon fanfic). I thought she was a sucky character in my head, but then I wrote down a few scenes with her in it, and I'm pretty sure I fell in love. XD
Okay, that's an exaggeration, but I know that she is the best character I ever created!
I know everyone, no matter how much they deny it, is guilty of creating at least one Mary-Sue. I'm glad you had the guts to admit it. XD
My good writing didn't start until I was about 14 with the realization that I HAD been creating Mary-Sues. Once I stopped myself from that, though, people really started enjoying my writing and now it's actually even MORE fun to write! Of course, I always put a bit of me into my characters, like most writers do.
Unfortunately, because of this, I sometimes get accused for making a Mary-Sue. Though I think that's mostly because I pair my Mary-Sue up (in romance fics) with the character I like. If I didn't do that though, I'd never want to write because then it'd be boring.