Sometimes even when you are giving your best, it doesn't seem like it's enough. When I was a physics major in college I spent 4 long grueling years trying to wrap my head around this subject and for 4 years I never really understood it. I lost sleep, went to the math workshop, asked teachers and friends for help, studied non-stop and still was barely able to pass with a C. The one thing that got me through was knowing that I was giving it my absolute all and as long as I did that I would end up exactly where I need to be.
Fast forward 3 years later and I have learned so much about myself through experience, self-reflection and meditation that I have realized the purpose of me pursuing the field of physics wasn't to be able to comprehend it, but rather to push me to my limit. I needed to understand the metaphysical side of energy before I could understand the physical aspect of it. But it ultimately pushed me down the direction to discovering that aspect of myself.
I wouldn't change the experience for the world because it made me who I am today. But only because I gave it my absolute best and deep in my heart I knew that I couldn't have given any more than I did. Do your best and figure out the path that you are guided to go down and you will eventually get there.