From the information you have given, it appears that you should file a motion challenging the warrantless entry into your room, and also a motion challenging your in-custody statement. It is likely that the police will claim that they made the entry as "community caretakers" who were concerned for your safety. That is an issue of fact, though. Similarly, you should file a motion to suppress your statement on the grounds that you were not read the Miranda warning.
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The legality of the police entry into your room and thus the viability of any challenge may turn on the fine print of the dorm rules, and if all you have is a non-criminal underage drinking citation, you not only won't likely have any viable fifth amendment challenge to your statement, but you can also be called as a witness against yourself at trial. Your post does not provide enough detail to determine what the officers relied upon for probable cause to arrest, but do not post more detail here in this public forum. Schedule a confidential consult with a defense attorney instead.
If nothing else, this should be a lesson in why one should never talk to the police.
This answer is provided for general information only. No legal advice can be given without a consult as to the specifics of the case.
I agree with Attorney Witt's answer. You have not posted enough information to definitely say whether there is a valid suppression motion here. But, you should not post any more information online. Anything posted online may be used against you in court. In fact, this post makes you easily identifiable; and you may want to consider asking Avvo to remove this post.
I would add you do not need to be Mirandized unless you are under custodial interrogation. In layman's terms, this means you were not free to leave and were being questioned in a manner that could incriminate you.
Finally, here is an excellent, but lengthy video, on why you should not talk to the police: http://www.youtube.com/watch?v=6wXkI4t7nuc