There’s a world of knowledge out there and it all intertwines—to study one subject, one begins to touch on the boundaries of others—and then does one study that new subject, too? There’s too much knowledge out there for any one person to know everything there is to know and to read everything that has been written.
At some point you have to stop looking for something new to learn, some new answer and start trying to figure out what answer works for you—the shift from merely accepting the work of others to beginning to explicate your own voice.
If you are trying to write a dissertation or thesis, that time is now.
The faculty do not set you on a dissertation expecting you to read—they expect you to write. The criteria for getting your dissertation accepted is not based on what you’ve read, but on what you have written. Of course they expect you to have done some reading. But the dissertation is about writing—it is about completing a written work.
Think of it this way: which person is more likely to have their dissertation accepted:
person A, who has read everything there is to read on his/her subject, and has written only an incomplete dissertation draft
person B, who has written a complete work that only uses a handful of sources?
The answer is obvious: person A has no chance of having a dissertation accepted, while person B, has a real chance of getting his/her dissertation accepted.
At some point you have to stop reading and researching and start writing—and what you use to write is your strengths—those things that you have studied, and especially those things that you know best.
None of which is to suggest that you don't need to do some research and some reading--there's got to be something to serve as a foundation for your strengths--something beyond personal conviction. But once that foundation is there--try to use it!