How can I personalise my bedroom?

Well we've been living in this house 4 ages now, and my mum keeps saying she isn't gonna get any decoration cause we're still renting! my room has a king size bed with a white butterfly duvet and a bedside lamp (my mum finally got 1) I can't be like any other teen and live in a tidy mess, my mum always makes me or cleans my room and it looks SOOOOO boring and white my closet isn't even in tht room :O there's 1 but its rly small, also have an en suite bathroom rly boring as well, oh and I do have posters but they don't make a huge difference.what can I do to change things up a bit, cause whatever I do my mum 'tidies' meaning ruins everything, so pissed offf so any ideas? Xxxx