Ella, Have you considered low blood sugars?. Your diet doesn't look to be an issue, it's possible that your fast metabolism, (which suggests you're a fast oxidizer) could be the issue. The 1st site explains the oxidizer types, the 2nd and 3rd sites explain a balanced approach to food consumption.

Oxidizer
http://www.drkaslow.com/html/fast_oxidizer_diet.html

The blood sugar diet
http://www.totalweightlosscenter.com/forms/WeightLoss/Week4/Blood_Sugar_Diet.pdf

Balanced oxidizer diets
http://www.livestrong.com/article/315489-balanced-oxidizer-diet/