You're right, you probably won't get into medicine.
Not because of your grades, but because of your character. This post either tells us that you are the cockiest person alive, and therefore would be unsuitable when it comes to serving others. Or that you are a defeatist, in which case, you won't have the grit to stick it out. Either way, you have to change your outlook on life, because a bit of humility and courage can go a long way.
I hope intelligence like this isn't wasted on someone who can't value or use it. GCSEs mean nothing in the end, you could literally fail every single one and still get into college. A-Level and Uni is where it counts.