Confused and puzzled getting, whole, concepts, advice

dvilayphet

1. Firstly, I am absolutely lost in the world of formulas. There are so many that it takes a whole day to even count them.
2. Secondly, I am scoring 70% (slightly more) in Practice Exams and Sample Exams. But it seems like there are a LOT of concepts I suck at. Maybe I am just getting lucky thanks to 3 answer choices.

Morale going downhill. Any advice guys?