Referring to your knowledge of "many top universities", you should probably also like to know that many subjects are considered 'undesirable' (like Media Studies, Film Studies, Theatre Studies, etc.) unless they have a direct relevance to the course. Taking traditional academic subjects (for many people) would be far more useful (because the skills required are more difficult).
That tells you that you are stronger at Maths, and weaker at a written subject like Business Studies. Some of the most challenging subjects at A-level are Maths (and Further Maths), the Sciences, and English Literature. I do not deny that Business and Economics have their strengths (in fact they do), but in general they are not as difficult as some more core subjects.SUrprisingly, it goes from one of teh easiest at gcse to one of the hardest at a level for which i can assure you off. Core 1 and 2 and decision amths are far easier for me than business and economics, especially th ebusiness side.
Again, your lack of knowledge of these "top universities" is amusing. All 5 of my offers have specified three grades only, with 4 of these offers being from some of the best universities in the country. I'm studying 4 subjects at A2, but you do not need any more than three A-levels. I would encourage as many AS courses as manageable in first year, but for A2 it's pretty futile as the universities don't have much of an indication as to what you might get in your new AS subject and wouldn't be particularly relevant anyway. Your second year should be spent focusing on the 3 or 4 A-levels you have taken, in my humble opinion. Why? Because it is these that determine whether you will get your university place.Next year i plan to study further maths in AS as well as my 3 A2 courses. Mainly due to it looking good on your UCAS application should you go to university. It can also show your willingness if you take a fifth AS to study harder (not only that, it gives you a greater chance of admittance to uni because many top universities want a B at AS in a fourth subject)