I wonder if what is at the heart of the problem is that you lived there “first” with other people with other rules and as a result, you feel like the place is yours. I can see how it could be difficult to be in the same place with a different set of rules.
It is, however, university housing, so you need to think of it as all four of you being in a new place (as familiar as it feels!) The 4 of you need to agree to the rules you will live with.
It sounds like one of your roommates is very neat and has made the rules. They sound like rules that will work well but it’s important that all 4 of you agree to them. You could ask for a meeting, explain that it feels particularly awkward for you to learn that rules have been made without your having been part of the process and alienating to find you are breaking them, and ask for clarification on what those rules are. If you have any requests (on noise, lights, etc), this is the time to raise those. Emphasize that you want to be a good roommate.
Whatever happens to your things inside your bedroom is up to you, but you will have to do what the group wants in the common spaces. Good luck.