Your dissertation is not just one big paper after you finish 2 years of coursework. Your dissertation is 2 years of lots of little term papers spread out in every class, culminating in one large paper at the end.
Revise your thinking.
Revise your approach to your PhD.
Use all 16 of those little term papers to build the underpinnings of your dissertation. It’s a simple equation. How many classes do you have to take? Home many will likely have a term paper or literature review associated with them?
You may be restricted in topic selection in some classes, but there’s is flexibility in most. Brainstorm all the sub-topics, the related topics, the various null hypotheses that can be tested for your dissertation. Plan ahead for the various papers you could do for all your classes.
Think ahead, folks.
It’s not that hard.