I have those tendencies too and also had problems with grad school.

I quit the program at one point and called a professor to tell him that I would not be making a presentation with my group that Monday. I can't even remember what he said, but it made me reconsider my decision. I was able to withdraw my resignation and continue.

I wound up just going through the motions with the program and it was 100% okay. Sometimes the bare minimum is good enough. What does it matter, in the end, if your thesis is perfect? If you've put years into the program, just get it done and move on. You are far more likely to regret quitting the program than you would regret taking six months to crank out a less good enough thesis that gets you a piece of paper saying you finished.

I'm obviously not familiar with your situation, but this happens to so many of us. I can't tell you how many people I know (including me) who put off taking their last class for 2-3 years!

Is there a career path that interests you?