What should I do about my roommate who wears tight clothes and describes her body, given my repeated but fruitless attempts to advise her, and my inability to end my relationship with her or change rooms?

If a girl wears tight clothes that describe her 'awrah in front of other women, she must be advised and informed of the Shari'ah ruling. If she insists [on wearing them], the general principle is to distance oneself from her. However, if there is an awkwardness in doing so and her continued presence does not lead to fitnah, then it is permissible to remain with her, while disapproving in one's heart and continuously offering advice.