Roommate Advice??

I'm in college and I live in an apartment of campus with three roommates. We all pay the same rent and same electric bill (not water because its including in the rent since the apartment complex is mainly for student living). Over the past couple months two of my roomies (who are bffs btw) have basically took control over the decorating of the living room. Which I didn't really have a problem with because it was just some pillows and throw blankets and candles, and everything was pretty cute (our apartment was already furnished so we didn't need to buy a couch and stuff, but they did bring in an ugly futon that doesn't match but I didn't say anything about because it was free).

Anyways, after Halloween I asked them if we were decorating for Christmas and if so that I wanted to contribute to the decorations because I love Christmas. I mentioned to them that I wanted a medium (decent) size tree for the living room and I that I wanted to move the furniture around in order to place it in the corner of the living room. I also told them that I was going to ask my grandma if she had an extra fake Christmas tree because my grandma likes to hold onto stuff. If my grandma didn't have an extra one, I wanted for all us to pitch in for a tree or I would just buy it myself and they could get some decorations for the room. Well my roommate, Ariana, went Christmas shopping last weekend and I figured she was going to get some wall and table decorations, which she did. She got some letters that spelled out Merry Christmas and hung them up on the big wall along with four stockings that had everyone's first initials on them, and she got three mini gold trees and put two of them on each end of the tv stand and one on the coffee table, and a couple other table decorations. And that's all fine. It's pretty, it's cute.

But I hate the tree she got. It's this two feet tall (maybe taller idk) and it looks like a tree that belongs in an office space. Its placed beside the futon and is right there when you first walk into the apartment. I mean, yeah, its cute and adorable and it had lights already made with, and, again, it would be perfect for an office space because of how small it is. But, in my opinion, it's awful for living room and it does give off that "Christmas feel" at all.

And I have no idea how to tell Ariana that I don't like without sounding like an awful person but, if I'm being honest, it actually hurt my feelings that she got a small tree after I told her that I was trying to get a medium size from my grandma or I was gonna get one myself because I wanted that Christmas vibe. I also wanted to have a decent size tree and, maybe, for all of us to decorate it together as a roommate bonding thing or just something we could all do together because we live together. It just hurts that she ignored the fact that I had expressed multiple times that I wanted a decent size tree.

And now its basically just been her and my other roommate (Jillian who is her best friend) who's been decorating the living room and they didn't even ask for mine or our other roommate (Kellie's) opinion on what we wanted (though Kellie is chill with anything). And this whole time its been Ariana and Jillian who's been decorating and they just continue to ignore what I want to do and whenever I bring something into the living to contribute to the living room they move it, as if to hide it, or they place it on the counter closest to my room telling me to take it back to my room.

And I don't know how to tell Ariana and Jillian that this is a problem because the living room feels more like it's theirs instead of everyone's. I mean, I understand that they're best friends and its probably exciting to decorate things together but I just wish that I would offer to include me in the ideas for the living room because its everyone's space.

So, does anyone have any advice on how I should bring this up or if I even should? Because I actually hate conflict and I have bad anxiety problems and they know this about me, so it also feels like they're walking over me. And I also just really want my tree because I love plump and big Christmas trees and I love decorating them.