Also, just to add, a B at AS isn't bad at all, everyone tends to get a grade higher at A2, so people who get B's at AS get A's at A2, and people who get A's at AS get A*s at A2, so even if you kept doing as you are, you're on track for an A, if you want an A* then you'll just have to find that little extra something in your revision and the exams, which is far from impossible