I agree with both Karen and NW. Counselling can be a great deal, since the counsellor can give you new insights in life. I can relate to what your saying, since some of the things you describe sound so similar to what I had (and still have). But as NW said, doing positive will make you feel positive. It is as simple as that. The only problem with anxiety and depression is that doing positive can be hard, very hard.
Maybe you could set yourself little and easy goals, like eating just a little bit less than normal, do sports, talk to someone you don't know etc. Fulfilling this goals will make you feel better, because the positive energy of that action will be transferred to you. On thing on this though, I found that it is very easy to blame yourself when you "fail" to achieve even that tiny goals. Blame is no solution, for nothing. It is just an evolutionary handicap giving to us to feel bad when things aren't going the way we want them to go. It serves as a purpose, but since we have consciousness, we can actually train our selves not to feel bad, but rather to experience the feeling, and accept it. That way, we are still aware of the things going on, but we won't have the negativity attached to it. Realizing that can give you an inner calm that will always be there as long as you stay aware.
I have found such a calmness in me. I am in the first year of university, and never been with people of my study outside school times. Sometimes I think people will think of me as a loner, a loser, or whatever. No matter what I think when I am at home, alone, I will always be aware of that inner calm that goes so much deeper than a periodic feeling of sadness or anxiety. That inner silence makes me aware that things aren't bad as long as you don't threat them as bad. Since every question has either a solution which you can pursuit, or no answer at all so that acceptance of that fact is all that is possible. When I am alone now, it is ok, since I can always call others when I feel I need that, even though I am not sure they like me.
And about that motivation problem, I have the same with my study at the moment. I, however, found one thing that has my unconditional love and attention, it is called music. Music is where I fall back to when things aren't going well on the outside. Are there things you always wanted to do? Things you always loved to do? If so, start doing them again. Start thinking of stuff that used to make you happy, and do it. Do it, and see the affect it will have on you.
All the best Brunette, and good luck with your study!
Acceptance is the key
Existential depression and Insecurity
Try to keep smiling! :)