No improvement in productivity despite being consistent

I am preparing for an exam which requires me to be productive for 8-10 hours studying various subjects. I have made some changes to my lifestyle in order to achieve this and can say that I am sitting down at my desk for roughly this amount of time everyday. Now, the problem is despite sitting for long hours, I feel like I am doing nothing. I tried tracking my study using ypt or forest but I am not able to see what I am doing wrong.

For a bit of background, I have issues with sleep and have been in a rut(study wise) for the past 5-7years. I also have a serious issues with consuming digital content especially TV series and Yt shorts, X and such( have been binge watching stuff since 2016-17 ). I am working on being better since the past year or so. These days I see this pattern recurring everyday that I make a plan for myself the night before and religiously follow it for the next 2-3 days, get exhausted and give up. It doesn't matter if I make the plan all in or take it one small thing at a time. I am not able form any long term habits and my productivity is in bits and pieces.

As I keep on trying, I am getting exhausted and getting tempted to give up entirely. But, there is this voice of conviction in my head that pushes me to try again, refusing to give up. As the time passes and I see no visible changes in myself, my conviction is getting weaker. How do I get out of this cycle?