Struggling with maths and further maths A-levels

Hey,
I'm in Y12 doing maths, further maths, chemistry and physics A-levels, and at the moment I'm really struggling with maths - we haven't even started any of the further maths content yet, and I've gone from getting 9's in maths and L2 further maths GCSEs and feeling pretty confidant about maths in general to getting less than 50% in my most recent exams. I kinda feel like I just don't really understand maths any more; most of the time in lesson I'm just sat staring at the screen wondering where my teachers got the last 10 lines from XD, and I'm so scared for the further maths content. It doesn't help that everyone in my class is a genius and gets everything that I don't XD. I'm tempted to drop further maths, but I'm keen on physical NatSci at Cambridge and I know that I need further maths to make a competitive application. I don't really know what I'm doing wrong and I don't know how to improve my scores.

Hey I feel this. Maths was my weakest subject (averaged a B) but I ended with 5 marks off of an A* in the final exams. Firstly, I wouldn't worry too much about the first few topics (basics). As long as you grasp them later and continue to work on them, you will get better. I believe the final exam questions (pure at least) were easier than those I'd get on topic tests. I didn't really pay much attention during class and simply made my own notes (my school used one note) and completed any practice questions I didn't get to finish in class. As you progress, the topics will start to make sense and interweave one another. If you check actual PPQs, they really test you on the most basic of concepts. Hang in there, it will get better.