Did the psychiatrist come just to see you or other students too? If it was a "group" thing you might not hear anything at all, what the school or whoever was testing for by having the psychiatrist come are looking for things in the group, not for/just you?

If you went to a psychiatrist that works at the school, like in a counselling center, if they feel you need help, they will call and schedule an appointment with a counsellor for you as soon as one opens up and depending on how your issues are compared with others. I went to my university counselling center the same day my next door neighbor dorm mate went and I was called the next day but she was not called for a long time because her issue was not as serious as mine. If that is the case, the longer you are not called, the more likely is your situation is not "bad" :-)

But in either case; I would call them if you would like to know! A week is plenty of time but be warned they will not tell you about yourself on the phone, just about when you can expect to see someone again to discuss your initial testing or clarification as to what/who the testing was for and whether your individual testing is going to be follow-up by them.