I think you should pay proportionally more rent since you will use common
area more and might have large/better bedroom and bathroom. Usually that
should be around $100-$200 more. For utility, usually 2/3 should be what you
shall share. But anything can be changed for different situations. It is a
frustrating problem indeed. But I think the best way is to talk straight
with your roommate and make clear that it is a fair share for each of you.
Such problems should be discussed before your roommat