Hello Jaos855,
I am currently studying GCSE's and these are the options I picked:
+ Computing
+ Spanish
+ Religious Studies
+ Statistics
I tried to choose a good range of subjects from a good range of categories. What I mean by categories are subject groups such as the humanities which would include subjects such as Religious Studies, History, Geography and even languages such as French, Spanish or German (these are the most common modern foreign languages taught in schools.)
When I was in this situation which was about a year ago since I am in Year 10, I went for subjects that I not only was good at but enjoyed also. I definitely like subjects that involve logic and require thinking and analysis since I'm a bit of a boring person! So you should definitely choose subjects that you have a genuine interest in and not only what you are good at.
Secondly, you should try to choose something that will help you in the future, if this is possible. For instance, I would like to be a lecturer in an University where I would teach Chemistry or Mathematics, depending on which I prefer by the end of GCSE's. If you do not have a dream job in mind right now, my next tip is be open with your subjects.
If you really cannot think of which one to choose, see what your friends are taking, think about what jobs they want to do when they're older, research these jobs and see if any of them fascinate you, and if they do, choose the correct subjects.
Sorry for such a long response but I know that it is hard when you are trying to choose what may alter your future forever.
Don't worry about the GCSE's, considering you are taking triple Science, you must be smart!
I hope this helps,
- mossysilver