Drop A-level Biology?!

I started sixth form in September 2017 and currently taking A-level maths, biology and psychology.

Biology just brings me an unnecessary amount of stress (i've gotten a couple white hairs from it!) and I am not good at it, the teachers and class isn't that great, I dislike the content and exam paper (too much to remember). Every lesson I try and enjoy it, but I find it impossible. I try to do everything to improve but it's not worth anything. I hardly understand anything and I honestly don't know why I took it because I only got a B in Biology for Core and Additional GCSE. My grades constantly vary: i've gotten a B before, but other than that it has just been D, E and U. I don't want to have to go into year 13 and my result be a D thus, preventing me to from going to the uni i want.

So, I want to drop Biology and do Business (because it's an easier subject and I'm actually interested in it because I want to do a degree in finance or economics). I proposed to my head of year that I learn business by myself in one year whilst continuing my other a levels; my sister has done this before and received an A. But he was very against it!

So, I was thinking to leave sixth form and go to college for year 13 because I want to drop biology so badly. So, I applied to a sixth form college but I already applied there last year and I don't think they would let me go into year 13 and do business with my 2 other a levels considering since I left them before.

i'm solid at maths (B) and psychology (A), but biology is a no (E).

I don't know what to do! Convince my head of year again or leave to a college that will let me? But i don't know if changing colleges is a good idea.