This is an easy question to answer. Somewhere, in all that ton of papers, you have a manual that your graduate school gave you. Go find it. There will be a chapter that is totally devoted to the preparation of your dissertation. Copy those pages, then cut the sections apart and tape each section to the front of an empty box. Now, start sorting all of your rough drafts and articles into the proper box, and keep sorting until you have the whole mess into boxes. At that point, you can begin to work on each section individually. By that, I mean actually write individual papers on each section. Don't even try to put them together in one document until you have each section the way you want it.
I also want you to make yourself a timeline. Chances are, you are using the scattergun approach and hoping you will make headway in time to meet your next timeline. I guess you've noticed that doesn't work. You have to plot these individual papers on a paper calendar, on which you can physically make notes. Once you have the dissertation broken down onto a timeline that will actually work for you, stick to the plan no matter what happens.
Don't overlook your advisors as a valuable resource for helping you. They have been through this hundreds of times and will be more than willing to help you stay on track. There is probably not a problem you have that they haven't heard before, so make an appointment with one, or more, of them and ask for help. That is really the only way they will know you are active and interested in finishing your dissertation. You will also find that you do better work when you are proactive about the entire process.
Am struggling with final discussion chapter of MSc dissertation
I have reached an absolute block here and am struggling with the structure of this chapter. I have tried working it up with the design and method disussion separate and then the literature and combined, but neither flows.
I would suggest that if you have hit a roadblock, try completely scrapping everything you have on the chapter thus far. Honestly, starting from scratch and trying a brand new method or thought process can and most certainly will help. It will give you new understandings and reinspire you. Stop what you're doing; rearrange your current set-up (or forget it entirely) and it will help you become re inspired.