I'm developing the same problems and feelings too! So you are not alone!
For the past four months I have been working on a fic myself 
and I've rewritten major parts of it at least 11 times!!!
I have also posted the same question
on here on the ffml three times in one day, wrote four long paragraphs
then changed my mind and deleted them and just found out 
I screwed up my sig.

If you're re-writing 11 times, you're overworking the fic, in my opinion. 
If you've written a major part, and don't like it, BEFORE you completely
re-write it, send it out to one or more people.  Get their feedback.  YOU
may think it sucks, but remember, you're only ONE of the readers.

I go through six phases.

1) I bang out the chapter/fic.
2) I read it over TWICE, and do whatever mid-level editing I need to make
me happy.
3) I send it out to my pre-readers.
4) They send their C&C, and I do a pre-post revision.
5) I post it to FFML
6) I get C&C (If any) and revise, then post to my web page.

Of course, before writing a fic/scene, I've got the whole plot outline
written in my head or on paper.  I did this in spades for some of my later
works, and man, does it show.

I think it has something to do with the three P's of fanfic writing:

1.Patience
2.Persistance
3.Proofreaders, lots of proofreaders!!!:)

Umm...not quite.  :)

1) Patience?   Have you HEARD these people when you take a hiatus on a fic
series?  I'm not Zen/Lurker...when people complain, I feel guilty.  I don't
like leaving things unfinished.  If I can't hack at tleast a paragraph out,
I feel bad.  It doesn't have to be a good paragraph, just a paragraph.

2) Persistance?  DEFINITELY.   Hell, if I let writer's block and everything
else that messes up my writing plans get to me on a regulat basis, I doubt
I'd ever have finished anything.

3) Proofreaders?  Heh...I have ONE.  His primary use is for
grammer/spelling on finished works, and he helps me develop plotlines.  I
suppose I should make good old Colin Simmonds my co-author, but I do 30x
the work he does...

Don't quit. Just let it go for a bit then when you feel you are ready
continue
writing. There isn't a time limit on this.

Just ask Zen. :)  

<Chris ducks>

Don't be afraid to post something.  That's what the FFML is for, to help.

--
Christopher Angel
cja124@mail.usask.ca      http://www.engr.usask.ca/~cja124
"Some will say you're safer here,
 Never mind them - be a pioneer!"