GCSE's are such a stress they shouldn't exist

I am literally stressed out right now for the amount of content I need to learn, I want to do 10 GCSE and my school is forcing me to do an 11th like if 10 is not enough. Most of my class mates are either doing 9 or 10. So let me explain, (i go to a private school, its not a posh one its more about it being an school just for girls, its really small) I have 23 girls in my year group and 6 of us got to choose to do Classical Civilisation. I thought why not I'll give it a go and I actually really love it and enjoy it. Now I'm not boasting but I'm pretty good at maths so my teacher suggested me and a few other girls should try out further maths, so one again I thought why not. So in my school we are not allowed to choose our own subjects unless we are given extra and want to quit it or another valid reason.
So one of the subjects they chose is Business Studies (i didn't know i couldn't opt out of Business before i chose my extra ones) , and i can not describe the hate that I have for the subject, it might mainly be because of the teacher (so she is the principles daughter so we cant really complain about her) so i am really active in every single of my subject lessons . However she doesn't allow us to participate in lessons and just reads from the slide and textbook. We started business studies since year 9 and we covered alot of content in one lesson.
Im not just the only one complaining about her its the whole school for a matter of fact past students have also vented to us about it. People that dont have extra lessons can usually catch up on the content at home but because of my extra subjects i cant do that. In year 10 i told her i wanted to quit because of having alot of subjects she told me that it was my own fault for choosing them and i had to deal with business or quit the extra ones but i didn't want to because i enjoyed them. AND IN YEAR 10 I HAD TO SIT THROUGH THREE PERIODS AT THE SAME TIME (one period is 45 minutes so X3 in one sitting).
I told my dad and he told me to fail the business mock so that i dont have to do it. That's true but i am scared they are going to take my other subjects away so i can focus on business. My school is literally obsessed with business.
But i dont want to be a business women I WANT TO GO INTO MEDICINE. And if i have a U on my GCSE no one is going to except me. But if they do try to do any of that i will put my dad on their case, he is a brilliant talker so i shouldnt be worried BUT I AM. I am usually deemed as the Perfect student but I am not perfect everyone has too high expectations of me, I try to tackle this by hyping myself too, but what if i am dreaming too high then what will i fall and crash and never be able to get on my toes again. I literally make no sense right now THATS HOW STRESSED, CONFUSED AND ANXIOUS I AM.
And anyways I really really badly want to do medicine, like y'all give me advice.
I know no one is going to read such a long post but yh, I am just complaining LOL.
aaaaaaaa GCSE's are such a stress they shouldn't exist.