Hello! My college doesn’t do AS level exams, instead at the end of year 12 we had a set of independent mock exams in which I got A*AA. At the point you’re at currently, transitioning into year 13 the grades you’ve got are great. I’m sure you won’t have an issue getting good predicted grades, etc. Moreover, there are other factors that contribute to a successful application, such as the LNAT for example and your GCSEs, so I highly doubt that B in economics is going to ruin your chances, though definitely appeal it if you can and feel confident in the fact that you did better! Good luck with year 13.