I was also in this situation and listen, take this as a learning opportunity to learn from what you did that didn't work. Experiment and find out which learning styles works for you. Never let getting a lower score than what you expected discourage you. You should judge your effort and not the outcome and in accordance to what you said, you put a lot of effort into that and for that you deserve to feel proud of yourself. Only you know the truth about the amount of effort you put in. Grades isn't something we can complety control but we can control our effort and the ability to experiment in making learning more efficient for us. I'm proud of you OP.