Your teacher is not qualified to make any such claims and should be reprimanded or at least reminded of this. But that is not at the root of this...
This is classic social anxiety, with likely a generalized anxiety disorder (GAD) -- these usually coexist with some level of depression. But I get so sick of that word, "Depression" -- it is far too general and isn't incredibly helpful and isn't much of a Dx .. But I digress.
Point is you need to take steps to help your self.
Exercise is the single best thing one can do for themselves to improve the mind. It isn't usually immediate.. in that you may have to do some cardiovascular exercise (ie: jogging, sports, etc) 3-5 times per week.. for 30mins to 1 hour per session -- for a month or two to start to really notice the difference.. but do it. It is excellent for your physical health, and it does translate into psychological well being. There have been numerous studies comparing a few months of exercise more effective than an antidepressant on the market (antidepressants are often used for anxiety as well). There is nothing 'bad' about it.
Improving your diet can help as well.. but don't overwhelm yourself with too much at once.
Don't ever deprive yourself of sleep if you have control of it. Getting 7-8 hours a night has a strong correlation with well being.
Think positive.. even though you think.. how can I? Or it doesn't matter what I do I always feel this way, and can't change it.. and so on. --- Still, whenever these thoughts come in.. accept them for what they are, and use your logic to rationalize things. Because in reality.. nothing bad is going to happen to you in these situations. Your body is reacting due to a psychological reaction that creates the 'panic' so to speak. These all build on each other to cause the social withdrawal because fear of how you will react, trying to protect yourself, trying to prevent the anxiety from being worse and so on.
But logically, so what? If you feel nervous and shakey and so on around others.. So what? What is the worst thing that will happen? They will laugh,.. maybe be immature and make a little fun? So?
What do you think they think while you are withdrawn? It is no worse I promise.
I only say these things is because exposure and making yourself (slowly) do things that are uncomfortable opens up the realm of being comfortable with these situations over time. It will be incredibly uncomfortable for a while.. but you can always make yourself do it.
Lastly -- see a psychologist! No shame in it. explain your symptoms, how you react, and so on. Therapy really DOES work. Believe it or not.. just talking and getting feed back from the professional DOES work. Again, this takes time.. but you combine all these efforts and you would likely see a HUGE benefit and you can get over these feelings. I promise!
You will have bad days and good days -- don't get discouraged by the days that are bad, or have no change. It will just make things worse. On any day or situation where things are a little better let that FUEL you to push on with these efforts. It is like climbing out of a big hole you've slowly fallen into over the years. It will take some time, and it may be a little while before you see 'light' but it is there..
Really, the psychologist is highly recommended. If you are still living with your parents, .. tell them, they should be more than willing to help you find the right one and help financially. That is what they are for. If for some reason you have no ties with your family -- all schools have some counselors on staff -- but generally these are not as qualified as seeing a true psychologist , especially one who deals with your type of anxiety problem/situation. But they can help nonetheless, and may be a good starting point. Your academic advisor could easily point you the right direction if you have no clue.
Also,.. this is EXTREMELY common among the general population in your age group, younger, and older generally the younger people suffer a bit more. From an age range of about about 10-49yrs or so.. but all ages can have varying levels of anxiety disorder.
You are not alone, there is hope, and this is essentially HIGHLY treatable -- even without medication.
I would also recommend looking into something called CBT, (Cognitive Behavioral Therapy) -- You can talk to your psychologist about this.. it is common, and sounds scary, but is not.. it is essentially just talking , learning tools to cope and get over things, exposure, and so on.
That should get you started!
Chin up,.. it is VERY uncomfortable and can be debilitating -- but it is totally something you can get out of, I promise.
