How can I convince my parents and brother to let me swap rooms?

My brother’s 13 and has the biggest room in the house, and I’m 14 and I have the smallest. It’s been this way since I was 6, so coming up to 9 years in May. We’re redecorating soon, and it’s been thought of for a while that I’d swap with him, seeing as I’m coming up to my GCSE’s and need room to sit and do my school work, and I just don’t have it in my room, unless I spread my stuff all over the floor. i don;t have enough room for anything and I just end up with everything going everywhere.
Suddenly, after suggesting it today everyone in my family is against it as my brother spends more time in his room, but most of it is when he’s asleep. I’ve tried to explain that I don’t spend any time in there because it’s just too small, but they couldn’t care less.
What can I do? I really need a bigger room, because all of my school stuff is downstairs, and it’s starting to get really annoying. What can I do to convince them?

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