Ditto :-(
I have gotten increasingly paranoid about this over the last while and for me it feels like, the more I learn the less I know. When in college, I am always really careful to minimise what's on screen whenever I leave my desk to go the printer or whatever - not because I think someone will steal it, but because I am angst-ridden over what people might think of it. A friend constantly leaves chapter drafts lying around and I admire him in a way 'coz he obviously has complete faith in what he's done! I was pretty confident about my writing ability at the start of the PhD but not so now.