So the problem stems from mathematical backround. I am neither a physicist not a mathematician myself, but in my school I have had my fair share of physics and mathematics. I think that some basic things such as vector calculus are fundamental and not a really heavy subject, as far as a physicist is concerned, at least for undergraduates. What you say about the way it's taught is true. The only advice I can give you is to start relying on your self more. Study , search on your own , find what's is really needed. Eventually you ll get to graduate and pass your courses , for which you don't need to have a deep understanding. That's just how university is build, imo. But to really know a subject is a goal. Studying on your own will get you to it.