Feeling sick, Eating disorder? =/ Options

[-TheKasbah-]

Anyway, this is the first time I have really asked for any help online. So anyway, here's a little background to what I think led to a suppposed eating disorder.

After last summer, a lot of my friends started drinking a lot more and this really annoyed me because they were becoming really unreliable. Much like my dad had while he was an alcoholic, he walked out on my family. So that basically triggered like a depression sort of thing for around 5 months, maybe more of when I was constantly feeling down and harmed myself a few times when it was really bad.

During the 5 months I had stopped eating as much and lost a lot of weight and I also got semi-somnia which is a form of insomnia brought on by stress. Lately coming up to exams when I have been really stressed, I have stopped eating again, usually about one meal a day and possibly a few snacks because I usually feel sick f I eat any more than that. I am something like 2 stone underweight and I am constantly stressed. It's coming up to my GCSE's in a few weeks and for anyone outside the UK, they are pretty much the deciding exams for what the rest of my life is like, so I could be doing without all these problems.

So if anyone could help me with a) What I might have and b)How I can help get rid of it.
I don't like the idea of going to the doctors so that's pretty much ruled out for now.

Any help would be appreciated, thanks.