I did 5 AS-Levels when I was in year 12 (I have just finished year 13). I chose Maths, Further Maths, Chemistry, Physics and Latin AS. There is no denying that it requires hard work to do 5 AS-Levels and do well in each subject. I chose to do 5 because I thought I enjoyed all the subjects, but the workload I had meant I wasn't enjoying Latin AS so I dropped it. In hindsight, I probably wouldn't have taken that fifth AS-Level as it seems it was unecessary. I would suggest you think very carefully about doing 5 AS Levels as it is difficult and I had to work hard throughout the year. Doing 5 A2 Levels would be a lot more difficult and could hinder your university application process significantly, so you should probably talk to your parents/teachers more about it. I personally would avoid doing 5 A2 Levels if you can.