I'm sorry if this is a little hard to read, my mind is a little wavy at times and hard to stay on one topic.

My (17f) family are moving in a month and a half. My sister (15f), and I have been fighting over the bigger room, which is a couple feet bigger than the other one we'd be in if not the big one.

At first, I was gonna take the smaller one, and just deal with it, but I made a couple comments about not really wanting that room, and how it's gonna be hard to put my geckos new tank, dresser, and desk in a small room that has most of the walls taken up by windows, and a radiator. My sister tried arguing with me, even though I wasn't arguing and my parents started getting sick of it, so they convinced my sister to take the smaller room, because she doesn't have as much stuff. We'll, my sister gave in, and now I'm supposed to be moving into the bigger room.

The only problem is that recently, my aunt and cousin offered a queen bed to my sister, and she talked to my mom, and my mom agreed. The mattress, plus a bedframe won't fit in the room, especially since my sister wants to get a vanity, and get a bigger dresser. So, my sister is arguing with me again to get the bigger room again, after I've already been promised the room.

Some background on my sister. She's the youngest of 5 kids, and although my parents deny it, she gets special treatment. She got a phone before me and my twin brother, when she was 12 (we didn't have phones then, the only reason we got phones was because she did), she got off with a warning when she snuck out of the house with her bf and ran from my parents the first night where my parents said we could stay up however long we want, and she gets gifts whenever. To explain the last one, she has gotten gifts and money on me and my brothers birthdays just because she cried, and because of all this, she's snotty, and for some reason allowed to insult us with no repercussions.

My parents keep making small comments about me and my sister arguing about the room, even though this is one of the first times I've ever spoken up for myself and not given in just because my sister is upset. My mom is more on my side about letting me keep the bigger room, and they'll figure out my sisters room, and how it'll be laid out so she can have her things, but she's still upset about us fighting, and my sister crying. My dad is the one making more comments, just because he's stressed from trying to make our house actually able to be lived in before we move into it, and dealing with the fighting since the situation as a whole isn't ideal.

Between the fighting, my dad making comments, and my mom's tired and defeated sighs while trying to reason with my sister, I feel like a bad person. AITA for not giving in?