I understand you completely, and you're not attention seeking, you're asking for people to tell you they get it. It's okay, we do get it, and you're most definitely not alone here
I've always aimed high, and always had expectations from so many people to be so much and do so much. I'm still feeling it as I wait for my a level results to get onto a competitive course.
But this is your summer to unwind, take a step back and decide what it is
you want to do and how
you want to do it.
Decaffeinated is absolutely right, your course is unlikely to demand all of these extra things at any other uni, and also that Cambridge is often just a badge, so please don't worry about not making it in.
One thing I can say with absolute certainty is that ambition cannot ruin you. Ambition can only drive you - it's personal fears and doubts that cause the turbulence. I can see that this has reached a point where it's all got on top of you. I've been there. I dealt with it in the most basic way possible. I stopped all thoughts and made myself answer the question,
why are you doing this?Write a list, draw a mindmap, whatever, just boil everything down to
what do you want?Redefine your idea of academic success, happiness and achievement as simply as possible (pleasing your parents should come last here, if at all). Only then do you need to think about how you might get there. Break it down into steps and stages. It's amazing how much less daunting A levels can seem once you break it down. Your current line of thought is a downward spiral, but it's also possible to spiral upwards too. The first stage is to take a break from everything to do with school and then you can take a fresh look at things.
Getting organised from day one of A2 (I sound so boring!) makes it so much easier. Do assignments as soon as possible, and go back over material often but only for short lengths of time. This will help prevent the tedium and will stop the workload piling up and looking scary
but probably the best solution for your lack of incentive is to find a way to re-engage with a subject. Make it interesting for yourself. People have no problem reciting facts or spewing verbal essays about their favourite musician. Why? Because they're studious? No, because they love the topic! I studied Physics, and I know it's really tough, but I made it into a game. I made solving puzzles fun, I followed IFL science because they bring crazy articles about Physics to my newsfeed, and I practiced questions so often that it became comfortably familiar, like someone asking you to recommend a particular model of laptop. You have to draw on knowledge, but it's all there because you've exposed yourself to it that often.
Step back, define your goals, search the quadrillion different courses you could do other than this one, break down your study and HAVE FUN!! I pulled myself out of the hole you're in now by doing this. I really, really, really hope it can help you. But if you take anything from this, just remember that this is all about
you.
Keep us posted please!