This is exactly the point I am in my writing. I've got my existing and about-to-be-submitted papers, and I've been moving text around, inserting bits here and there. I've gotta get my act together and actually make it look like a thesis and not a series of publications.
I stumble upon two situations which cause me grief: (1) the writing and rewriting of sentences that I already understand, but have trouble communicating an idea in a concise manner, and (2) just not knowing what else to say.
Situation (1) is not a fun place to be in. I get lost in time sometimes and get stuck on a sentence/paragraph for hours. Situation (2) isn't too bad, cause it clearly is a signal that I should stop writing, and work things out on a whiteboard, or hunt down articles and do more reading.
I mention grief, but it's not that I don't enjoy this process. Sure there are non-fun periods of time. But that's part of it. Overall, I have a vision in my brain how I expect things to turn out.
But my main adversary is TIME. I resent the calendar as the days are whizzing by now. I've got so much I still want to do, but there must be a point where I just have to stop the ideas and get the writing done.
