"I've been a vegetarian since I was maybe 5 years old."
and I think you wrote that on purpose cause you yourself are questioning the possibility that your symptoms are related to your diet.
I do not know what your definition of "vegetarian" is, but there are many people who call themselves vegetarian and they do not consume eggs or cheese or fish.
Anyway, you should know that anything you ever heard about vegetarian diet being healthy is true, if you are an adult who consumed fast food meat your whole life, and now you switch to a healthy vegetarian diet free from fast foods and hot dogs.
An adult may feel great for many years, and that may be the story of your parents.
Based on personal experince, your parents may have imposed vegetarian diet on you, in their best intention.
And, it could have been a good choice for you for many years.
The problem is, after many years, body uses up all reserves of stored nutrients from the past diet, and you endup malnourished.
If you have been vegetarian for the past 11 years, that is more then enough for most people to "run out of gas".
After 11 years on vegetarian diet, all benefits are gone, and you are left with health problems caused by malnutrition.
What you need is to include healthy, home prepared, animal protein in your diet. Cook food from scratch and avoid industrially processed meat.
If you are affraid to tell your parents that you are not vegetarian anymore, don't tell them.
Eat meat out of home. Eat with your friends at their home.
You do not need to eat meat every day. It is enough to take it twice a week, on average, but it will not hurt you if you take it more often.
Your symptoms will vanish after a few meals with red meat.
Red meat is rich source of easily absorbable iron, B12, amino acids ... and that is what your body needs.
Trust me, I am shark, I know how vegetarians taste like :-)