How confident are you in your arts subjects? You could drop one of the pure sciences if you're very sure that you can get A's in your other subjects. I dropped pure Physics in Sec 4. I made the choice not only because I was not interested and doing badly in Physics, but also because I could not engage a tutor. For the 'O' levels, I studied for pure Chem, Maths and A. Maths on my own and did relatively well. I don't think that the combined sciences are easier, as taking two different subjects usually means that you have more basic information to memorise.Alternatively, have you considered engaging a tutor for Physics and Chem? Since you passed the subjects last year, perhaps all you need is extra guidance to improve your grades? I know people who successfully turned their grades around after a few months of tuition in Physics and Chem. It's worth a shot.