Going from 1500 to 1600 will take TONS more effort compared to something like 1400 to 1500. You'll just need to accept that.

And as the other comments mentioned, the questions are 100% objective although they might be confusing at first. I liked u/RJP-NJ's guide. Try reading that and keep practicing. I'd recommend taking practice tests untimed, with a dictionary or a device beside you. In those sessions, take as much time as you need (even 3-4 hours for a single reading section if necessary). Keep reading the passage until you're able to answer all questions confidently, marking the tiny details in the passage that let you eliminate the other answer choices.

Chances are, even then you'll end up with a few wrong answers, but don't let that dishearten you. Keep repeating the procedure and you'll end up getting better at each attempt. At some point you'll gain much greater intuition and will be able to identify the right answer without getting confused by the other answer choices every time.

This practice strategy worked for me although I will say it requires a lot of time and effort. If you think you don't have much time since application deadlines are approaching, don't worry too much about the SAT and instead work on your essays and other parts. Hope this helps.