Have you spoken to anyone else on your course about this? Do you have support at home? I think if its go to the point where you're not eating you should really talk to someone about it who can make a difference. I'm training to be a teacher too, and sometimes i find it really really tough, and without my husband i would have been a nervous wreck by now. Find someone to talk to, and have the weekend off (if you can! at least some of it anyway), spend some time doing something you enjoy and this may help your stress levels. And eat something!