depression

I am depressed. I have major depression disorder.  I am not writing this for sympathy or attention.  I am writing it because maybe if I admit it, I'll actually get up and do something about it.
I have been in a slump since the beginning of the school year, when I panicked and thought I would have to leave my major due to something careless I did when I was younger.  From that point on, anxiety has been taking over my life.  I've been worried about everything, especially disappointing my parents again.  I started having panic attacks about once a week, typically in class.  It would start by the professor saying some kind of trigger word that would cause my heart to start beating really fast, and then I would get sweaty and nauseous.  My vision would get blurry and I would start getting fidgety.  The symptoms wouldn't go away until I eventually left the classroom.
Finally I was tired of worrying all the time, so my boyfriend convinced me to talk to my adviser and tell him what had happened so he could assure me I could stay in my major.  He did, and I thought I would start feeling better.  I didn't.  Instead of feeling constantly anxious, I felt tired and defeated and I didn't want to do anything.  I thought I was just feeling burnout.  I had midterms, sorority stuff, theater stuff, work, and a lot of personal issues back home.  I thought once I went home for fall break and relaxed a little I would go back to normal.  Unfortunately, over break I had 2 exams to study for, crafts to make for my Little, people to visit in the hospital, and my boyfriend came home with me so I had to entertain him.  When I came back from school, I was even more unhappy.  My anxiety got out of hand.  I don't eat anymore. My sleeping patterns are all messed up, I either nap for 6 hours or wake up several times in the middle of the night.. I don't like going out, or going to sorority events with my sisters.  I stopped caring about my appearance.  I can't motivate myself to study and do work, and even though my grades are slipping, I still can't study.  Even things like meeting friends for lunch feels like a burden.  All I want to do is sit on the computer.  I lash out on my friends and boyfriend, and I'm afraid they're going to leave me.  I think everybody hates me all of the time.  I don't feel valuable.  It just feels like there's no way out.  I don't think I've had a day where I don't feel like this since August.
I don't know what to do. I'm scared to talk to somebody at school. I'm afraid of people judging me.  I'm afraid of even scheduling an appointment with the counseling center.  I don't want to tell my parents because they have enough to deal with at home and I'm worried they won't believe me.  I can't just turn a switch and change my thinking patterns.  I'm hoping if I can at least write down what I'm feeling, I might feel a bit better, but deep down I know the only way I'll get better is if I talk to a professional.
I know this is way different from feeling sad.  When I'm sad, I typically feel better in a few days, and I get over it by talking to people, going out, watching movies. I don't want to do any of those things. This feeling hasn't gone away for weeks.  It feel like there is a little rain cloud over my head all the time. People are starting to notice I'm not the same, but I blame it on tiredness.  This isn't me being an attention-seeking girl.  This is me being really scared and hopeless and unhappy.