It's just the 'new kid on the the block' feeling. You're entering an environment at a point where a lot of people already know each other. Could be they know each from previous classes, dorms, or what not. I've been in similar positions many times in college. Just give it some time. My best suggestion would be to find the groups that are focus on earning the same degree as you are, and causally let them know you are heading in the same direction, it might even take a quarter/semester for you to become 'recognized'. Just hang with it, do your thing, and it will happen.
Also watch for 'department-related' activities. When I was in college the department my degree was in often had activities to get to know each other. We had potlucks, Halloween parties, ice skating days, and so on. There was also a professional society that was hosted by the department and they had quarterly meetings for new members and often included pizza, and was very causal.
But mostly, just be there. It won't take long before someone will take an interest in the person they don't know but see everywhere.
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On the Spectrum since 2003.