I'm sorry things are so tough for you .... but what you need to do is take care of YOU. I know it sucks eating alone - been there, but it is SO important. if you dont eat, you wont have energy, and that could be partially why you feel more tired all the time.
As for the other things ... do you have any hobbies? If you can find time to maybe even do some of those, you may feel better. And like constant said, there are free counsellors at your school to talk to, or even just writing (like in a journal) can help to get some stuff out there. I know when i am feeling really down if i can sit down and write, and see everything on paper .. i feel a little better just knowing that its not AS much hidden inside of me. - but thats just me, you need to find something that works for you.