My advice.
Focus on the GCSE's that you want to do, and will benefit you in the long run.
Personally, I did 11 GCSE's (incl Maths and English) and they only really help in securing your A-Level choices.
Once you hit University, GCSE's play a very small part in enabling you to take a subject.
Any jobs after that, GCSE's are irrelevant. My CV literally just says '11 GCSE's ranging from B-D'.
Moral of the story, will these extra GCSE's really benefit you in your future career?
If yes, take them, but be prepared to put in more effort than your friends.
If no, then focus on the ones that do matter, and work towards that goal of securing a good education.