Don't worry, it's normal to feel stressed out while preparing for exam.
From where I see it, it seems as if you have trouble focusing and lack direction. Therefore, I would suggest that, first, you download syllabus for all the subjects you are taking.
Secondly, divide the topics on number of days you have for preparation, and stick with the plan.
Thirdly, don't take advice from everyone, pick one strategy that feels the most efficient and then just follow it.
Lastly, for essay, start by writing introduction of topics in the past papeds, after your mind gets in the flow, you can practice writing a complete essay. Reading essays from writers like Francis Bacon, charles Lamb might help get an idea on how thoughts are put together in an essay. Another way is to make outlines, and wrote a shorter essay first, for example 1000 words, and slowly moving up to 3000.

I hope this would be a constructive start for you. Though, finding a competent CSP to guide you is always a bonus.

In the end, I would just say that rather than worrying about what you can't do, focus on what you can do. Stay motivated and follow a plan single mindedly. Goodluck.