If you've only taken 8 tests, then you've only gone through around 400 questions or so. You've got another 2500 or so questions to go through between the remaining 50 or so preptests that you haven't worked through. Keep working at it! You'll get there!
I don't think going through another 2500 questions if you're still not getting it is a good strategy. REDO the ones you've seen already and get the concepts down before grinding through another huge set of them.
Right, I wasn't recommending grinding through another 2500 questions haphazardly. I was just trying to reassure and encourage the OP - they still have only had limited exposure to these types of questions, and they have plenty of material to work through to improve. The familiarity with the questions that comes from experience makes the LR section much easier as you progress through your preparation. Having said that, EarlCat is certainly correct - go through the questions that you have worked on already and be sure that you are fully understanding them. Why did you get this question wrong? Why did you get this question right? Are you making the same mistake over and over? What question types are you having difficulty on? In order to improve, it is essential to understand where/why you are making mistakes and (perhaps just as importantly), where/why you are excelling.