How do I tell my roommate I deserve the bigger room?

So I'm about to move into my new apartment and my roommate wants the bigger room. I feel that I totally deserve the bigger room because I found the apartment, im the one that called 20 apartment places, I've also been on top of everything and I've had to remind of her of pretty much everything. honestly I feel like the adult one here. And she's pretty much going to end up using a lot of my stuff like kitchenware because she hardly has anything.

I want to say it politely to her because sometimes she's moody. So how should I politely but sternly say I want/deserve the slightly bigger room?