hi and welcome to beyond blue.
the university environment is a lot different to high school - the lecturers might not care if you do not turn up, you are responsible for many of the things you have to do including time management, attending lecturers, research for assignments etc. Assignment wise, the expectations of lecturers is typically a lot harder compared with high school. So sometimes that first year is a time of getting used to everything. All of these things can contribute as stress.
Om talking to friends from high school ... Going to Uni is another stage in life and people from high school days can go in their own directions as well. When I was in a share house in my Uni days, the people I shared a house with did not really chat with people from high school.
In relation to symptoms and signs, that is something I would tend to leave to the experts when it becomes more then anxiety and depression. I have done what you have done and chatted about it with my psychologist. It can be easily to read an articles and see things in what the author is saying and then convince yourself that is you also.
If I could make one suggestion... have a chat with counsellors or similar from student services. Perhaps there are some groups you could join and find people with similar interests to you. What sort of things to do you like to do for fun?