Roommate?

I don't know where else to ask... But I'm moving in to an apartment with my friend for the first time... She has a baby. We're going to be getting a 3 bed 2 bath apartment and splitting the rent and utilities in half... How do I tell her that I want the master bedroom? She's going to get two bedrooms and her own bath already. I'm getting 1 bed and the other bath. We are paying the same exact rent so wouldn't it make sense if I got the master with the private bath connected to bedroom? I just feel so selfish and its seriously stressing me out. Help...