NS4 is known to be the harder of the NS exams so you're in a good place.
CARS on FL1 is known to be pretty harsh too. I would just drill the SB's if you haven't already and get used to how the AAMC writes their questions. Also the CARS Qpack would be helpful for you as well. I think you're in a good position for a 515+ if you're able to use the rest of your time wisely.