I had the same problem when I was starting Sixth Form, which is why my Head of Year told me I'd always be remembered as the girl who wanted to do nine A-Levels!
I know how tricky it is when you want to do so many different subjects, but there are some things to bear in mind.
One of these is that some subjects are (sadly) seen as 'soft' or 'easy options' - if you think you can cope with the work and you're unsure which subjects to choose, you'd probably be better off picking as many facilitating subjects as possible to keep your options open. That doesn't mean you have to completely avoid anything which isn't sciencey or English-y - usually, universities recommend that you don't take more than one or two non-facilitating subjects, so you still have room to pick a less demanding option.
Another thing to consider is the idea of picking either a range or a complementary group of subjects: for someone intent on studying sciences, it's a good idea to take subjects in this area, but if you're not sure you could go for a mixture to show that you have a range of skills. I studied French, Maths and RS (with Spanish at AS) and found that, even though they were very different, they all complemented each other well. If you know what you want to study at Uni (if Uni is your plan post-college), DEFINITELY browse Uni websites to see which subjects they require you to have studied or prefer you to have. When I had finished my GCSEs, I found a useful booklet online about post-16 subject choice - there might still be one out there if you browse Google!*
Also, the EPQ can be helpful to cover some of the things you lose by dropping a subject you wanted to take - I really wanted to study English Literature and Drama, so focused my EPQ on 'Much Ado About Nothing' by Shakespeare.
Hope this helps
P.S It took me a couple of weeks after starting Sixth Form to finally make up my mind - I went in on enrolment day with six subjects in mind, and kept changing between Spanish and Drama after I'd already started. A-Level choices are a big decision, so don't worry about being indecisive straight away - it will all work out in the end
*Found it!
http://www.russellgroup.org/InformedChoices-latest.pdf