i agree with what the other user has said here
I take bio,chem,maths at alevel for med i am in year 13, i would say just in general i really enough bio and chem i wouldn't say it is a very big jump form gcse but as you already probably gussed there is a lot more to learn and the concepts are harder like with any subject but i really enjoy bio and chem still if you put in the work they are fine subjects.
honestly, if you’re even slightly considering medicine, i’d really recommend taking chemistry, most medical schools require it, whereas SALT doesn’t, so chem keeps both doors open. you can still go into SALT with bio/chem/english, but you can’t really do medicine without chem.
from what you’ve said, you clearly can do chemistry ,getting a 9 in organic after revising it yourself shows that,a-level chem is hard, but it’s more about understanding and practice than being “naturally good”. if you’re willing to put the work in, you should be fine.
also, you can always drop chemistry early in year 12 if it turns out you really hate it, but it’s much harder to add it later. so i’d say take chem now to keep your options open.