Hi and !"£
Perhaps part of the problem is that you feel guilty because you got what you wanted, only to find you don't want it - an awful feeling. But give yourself credit for achieving your goal at least. I can understand how you feel trapped in it now though, especially with the current state of the economy. Could you start making a long-term plan to get out of it? At least then you might not feel so trapped and that things can never get better. Meanwhile, as lightenup says, I think you need to find something you can enjoy doing to try to take the focus off how much you hate your job.
Re bulimia and overeating; I was bulimic for about 10 years, eventually I saw my doctor about it and was prescribed a high dose of Prozac, which (to my amazement!) "cured" it. I now eat normally and do not have a weight problem. Of course the bulimia is just another symptom of depression and you will still need to deal with that. As you started depression at 10 years old it clearly has deep roots, but you can get through it. I'm glad writing on here has helped; keep posting!
Best wishes, bel