Hi,
I teach Academic English at university so I can’t directly help with the GSCE part. But I do know about studying. I’m wondering, do you find the material difficult? Are you able to concentrate/focus for extended periods of time? How much time do you realistically spend on your ‘studies’? They are many many ways to study, not necessarily just sitting and reading for hours, which can be counter productive. Can you break down all the various activities you conscientiously do to contribute to studying?
When you have some realistic and truthful answers to those questions, you may benefit from a study/rest/leisure schedule. Research has shown that developing a timetable for your self which includes rest breaks and things to look forward (and isn’t just packed with overly ambitious study periods) can help you structure your time, your learning and help you retain the information. Also, attempting past papers and getting thorough feedback on them will really really be good for you.