Okay, first and foremost, you will never know everything for the test. What's most important is that you are practicing the skills you will need. Practice passages are your friend! At this point, you should be transitioning away from content review and doing more and more practice.
Make sure to set aside time to do practice tests in test-like conditions (be somewhere quiet but not too quiet, only take the allowed breaks for the correct amount of time). Think of what you will bring to the site (food, beverages) and take a least one practice test that mimics the real one including the food/water and timed breaks. I did one full-length practice test every Saturday for 5 weeks prior to my exam, and I think that really helped prepare me emotionally. But don't just take the test and forget about it or stress that you didn't do as well as you wanted. Make sure to go over it and understand why you made the mistakes you did. Then you can figure out new strategies to approach those problems. It's less about memorizing content and more about close reading, understanding the methods/results of the experiment passages, and recognizing when the passages directly give you the answers.
General advice to all: DON'T DO ANY STUDYING FOR THE 2 DAYS BEFORE YOUR TEST. Seriously. The day before my test I went to see the Star Wars movie, went out to lunch, and hung out with friends. It was the best choice I could have made because it allowed me to enter the exam wayyyyy more relaxed than I would have otherwise. If you feel like you must study a bit, you can do flashcards or something on the 21st, but don't cram! And don't do anything on the 22nd!! It won't help and will make you so much more stressed.
On the actual test day, allow yourself to relax. Smile at people when you are waiting to start. Depending on the vibe there, crack a couple of jokes. It's really important to start the test in the right mindset, if possible.
Most importantly, breathe!! It will all be over soon. 🙂
