Wheel Bearing Problem, Should I be driving it?

Hi. I have a 2003 Nissan Micra 1.2. Recently, I have noticed a loud humming noise from the rear left wheel which everyone seems to think is the wheel bearing. The noise only occurs below 30, and above, but not at 30. The faster I go, the louder the noise gets. I can generally hear it above loud music. I drive it slowly as I am worried about it but I am strapped for cash lately, I can't afford busses so I really need this car to get to college but I am worried something is going to let go and cause me to crash. Is this the wheel bearing and what are the implications of driving this? Appreciate your time. Thanks.