I've moved rooms and now feel uncomfortable, what do I do? It's a bit long sorry?

I've stayed in my other room for about two and a half years or one and a half because my brother had a load of rubbish in his room and he needed more space (my room I'm in now is bigger than the one he was in) so I agreed and his girlfriend came around a lot, the bigger room made it better so they wouldn't be in a tiny room. He moved out about two weeks ago and I'm finding it hard to cope without him, he was the only family member besides my father and cousins that I got along with, I mean, I adore my sister who's in Uni but I have trouble sometimes getting along with my mother. So anyways... My brother moved out and before he did I was trying to get the big room back, knowing he was leaving, but my mother kept saying no to me. So I got the big room in the end when my sister kindly gave it to me. I moved in yesterday and it took me about one o'clock in the morning to sleep, I just couldn't feel comfortable. It's a big cream room with dark cream carpet and a bunch of new wardrobes and a new desk, it feels heartless. My old room was small, blue, cream carpet and had posters all over the place and in my new room because my mother had it painted by some professionals I think instead of us doing it ourselves she refuses to let me paint it green, which I want to make it feel more homely to me and she wont let me put up posters until she gets blue tac which wont damage the walls. I feel really uncomfortable and irritable in the room, it doesn't look like a room I can go in and relax, it's all new and it feels like I can't do or touch anything because something might get ruined also it feels empty, like something's missing, I don't know if it's the posters not being there or it being a bigger room than I had been in but it feels cold to me. I decided yesterday, new room, new start. It's so hard! If the weather was nice and I wasn't in school I may be more comfortable I mean, I could stay up all night watching Family Guy until I can finally go to sleep but with school I can't. It has the new room smell which is understandable, I have new things and I have to wait until I get used to the smell or until it goes, but I usually have my cat in my room too and he makes me feel more comfortable and it helps that I don't feel as lonely but I still do, I think it's because I have to get used to it being big but I'm having trouble relaxing, my cat wont go in my room, he doesn't like to be in there I think or it's a change for him but he didn't last night and it was hard to relax, I felt like someone was watching me and it freaked me out a bit. Is there anything I can do? Why don't I feel relaxed? Please help someone?