what are you worried about? You have an average of 3.98 !!!!! How could that have been any better? I'd be very surprised if you don't get in with those grades. And they don't ask for GRE marks. It mostly your grades and your writing sample. But your grades are too good, they will confiscate even if your writing sample was bad. Which i dont think it is given how well you've performed. Just sit back and plan ahead for getting into Oxford. I'm so jealous btw. I wish I had grades as good as you. Then I'll just be booking my ticket to Oxford in advance.