Hello there, welcome back! =)

WBTB is quite handy... but yes, it is problematic if you have a roommate. You could try using a silent alarm, like a vibrating cell phone. There are also ways of training yourself to wake up naturally at a certain time. Or you could not do WBTB's and just focus on your dream recall and try to DILD.

Anyway, good luck! =D Feel free to ask if you have any other questions.