I currently do maths, DT and BTEC business. Chose maths cause I was good at it gives you alot of options. DT is my favourite subject, loved it GCSE cause it's quite practical and I had really nice teachers and it was one of my best grades. BTEC business is the one which I didn't actually want to do as much as my others, I didn't really know what to do as a 3rd tho .I originally did physics but wanted to swap for a level business because I was struggling and not enjoying it (I should have chosen business from the start tbh it was my highest grade) but it ended up clashing with my DT lesson and it was the only choice I was offered by my school. I wish I picked Econ tbh.

You could try to narrow down what subjects you want to by looking at what your being offered or what your studying now and cross off ones you definitely don't want to do and then rank the ones left in order of how much you enjoy the subjects then cross off the ones you enjoy the least then order them by how good you are at them. If you have a career or feild in mind look at what you will need for them.