Hey!
I was also on your boat too during my GMAT study time. From the ESR I could see that:
1. Your sentence correction is quite low compared to other components of your score. Luckily, SC is the easiest thing you can improve on in a short period of time. I suggest you to go through the questions you have practiced previously and dissect what went wrong. Try to study why YOU DID THOSE QUESTIONS THE WAY YOU DID and tweak your approach. For example, I used to answer sentence correction by ear even though I am not a native. However, after realizing by ear will get me nowhere I started learning grammar rules and reading up on how other test takers approach the question and became better at systematically tackling SC.
- TIP: Trying going through carcass' question bank and reading his explanations!
2. In terms of CR, the best for you to improve is know the questions type you will be tackling. AKA once you read the question you need to know what category it is and what type of wrong questions you could be seeing. The best books that covers this is Powerscore and in terms of online course it's
e-GMAT hands down.
3. You are rushing towards the end of the exam. The best way to fix this issue is work on the timing. For each question you practice you should not go beyond 1 minute and 30 seconds. This timing will allow you to feel a bit more flexible during the exam.
4. I can't really give advice on RC other than the same thing with CR... work on knowing what questions you'll be facing and how to systematically tackle them.