hi there gemnjam..
if it will be of any help, here is a confession: I have been in that exact situation for the past two years. (With all the extensions I'm in my some 5th year!!!). BUT- you have to deal with it and hang in there! Do not get carried away with feelings of guilt. I tell myself that this is what a majority go through (at least at some point in their phd) and that the ones that actually do get their phd's are a) self-centred, huge egos, that have never experienced a drop of insecurity/guilt etc. or b) the ones who have been through this self-torture and dealt with it!
hang in there and let me know what happens.
p.s. congratulate yourself for being such a sensitive person as well- the world of full of d. heads and know-hows
elfsu