Overthinking Things

I've been on writing.com a while, but I've not written all that much. (There's a link at the end of the article to my interactive chapters for anyone who's interested.)
My problem as a writer is that I find it difficult to focus on the actual writing, I tend to keep focussing on plotting, over and over, refining the plots to an ever more detailed height - but never actually getting round to writing them out. I think I'm potentially a decent writer, but I tend to feel self-conscious about my writing, and as a result, of the stories in my head, there are several I have planned in detail where I want the stories and characters to go, but I don't actually get round to the writing.
Like I said, I've written a couple of interactive chapters - one on a space opera around a character called Joseph Bliss, another in a scifi comedy, and a chapter in a zombie comedy.
However, my instinct to plot in detail before writing tends to take over - for instance on my old computer I had detailed plans for plotting for several chapters of 'The Body Swap Experiment' - an interactive story I never actually contributed to.
My main problem, I think, is that I'm conscious of my writing turning out badly, I'd find it helpful to be able to explain what I was intending to do when things go wrong.
The reason for writing this is that I need to change my mentality - and writing this will help me adapt a bit, knowing this information, this point of view on my writing style is out there to 'justify' my mistakes and bad writing.
If anyone has feedback and comments, I'd appreciate it.

Take care,

Maxwell Power
http://www.writing.com/main/view_item/action/show_chapters/user_id/dave0017