Parents are being frustrating

So I still live with my parents and we are on good terms. I’ve never had trouble with them that I couldn’t just brush off but I suddenly feel like I’m being brushed off and pushed away. My parents recently moved into a new house and I haven’t been home to decorate my side of the room, because yes I’m 20 and share a room with my 11yr sister, and I’ve been away at college. I’ve never had a problem sharing my room, and still don’t. Sure it would be awesome to have my own room but I’m fine with sharing. Well I noticed it’s supposed to rain for the next few days so I mentioned putting up my few shelves and pictures during those days. My shelves that I have are small. Two of them are only a foot long and the other is two feet long and they are all only two to three inches wide and are a single straight shelf. So not very big. At our other house I also had two very large shelves that were a foot wide and three feet long. So you can imagine how many decorations I have on them. Unfortunately we were not able to bring the two large shelves so I only have my three smaller ones. So as you can imagine, I have a bunch of stuff that’s not going to fit on them and I’m going to have to put elsewhere. All off my shelf stuff is in a box in my closet and my mom has been harping on my to unbox it and put them away. So when I mentioned putting my shelves up my sister said “yay I want to put my stuff on them too”. Well there’s not enough room and the shelves are going to be on my side of the room. I told her that she was going to have to get her own shelves because there wasn’t enough room for her stuff. When I said this my mom said “oh hush, you’re never even here anyways.” And my sister said “yeah because of college”. I paused because that didn’t make any sense. What does that have to do with putting my things on my shelf? I asked her “what does that mean? What are you talking about? That doesn’t make any sense.” And my mom just huffed and rolled her eyes. Like, is there something I missed in her statement? Am I just awash in hormones and I miss understood her because I’m taking this as her saying my side of the room isn’t actually my side because I go to college. Like why can’t she have her own shelves on her own side? For reference she has plenty of room for some shelves are her side. And honestly she needs them because her stuff is everywhere all over the room. And it’s not like I have a bunch of junk that I put on my shelves. Most of my stuff has been passed down from family members, some that have passed away. I like to have them where I can see them. Idk maybe I’m just hormonal but wth just happened?