Start taking vitamin E every night before bed and up your protein intake.
I know that a friend of my cousin tried going vegetarian.(because its a fad and all) She did it for about 2 years and started getting hair loss, She was like 17 at the time. Long story short she went to the doctor and he determed that it was because she had such low levels of protein in her body.
Stress may also be a factor so try and wind down and do something that will get your stress levels down. Go for a run or listen to music and have tea. Whatever you fancy.
Stress definitely can play a roll in hair loss as well as not eating. Stress can make you skip a hair growth cycle as well which can make your ahir even thinner. You need to start taking care of yourself. Even if you don't eat much start eating protein and maybe consider a supplement (of course only after speaking with a physician) Biotin has been known to help with minimizing hair loss during stressful times.
Many vitamins and minerals help hair growth, but specifically there are some stronger options than Vitamin E as studies show. It may be easier to buy a specific hair growth supplement that includes more than one specific thing. You should research Reloxe and other products that get results.