I’m in the same boat- 3A*s at gcse in my a level subjects predicted great things and I know in August I won’t even have c’s on my results - totally my own fault I lost all motivation for my exams.
I’m taking a gap year, my mum wasn’t happy with it at first, but I have a part time job and some savings plus I’m 18 so I’m not really sure what your siblings can do to stop you? As it’s your life and your choices if you want to take a gap year to gain life experience you do that?
Heading off to the Maldives for a month next week, then I come back and work until December, and then I’m off to south East Asia for two months through January and February.
Tell your siblings that it’s what you want to do, throw in a bit of “I want to find myself, and find what I really want to do in my life” and actually do something worthwhile don’t waste it away. At the end of the day it’s your life, you’re 18 so you can make your own life choices you have to make your siblings understand this