I find it hard to sleep, easily to get stress out, mood changes often, headaches often for 3 years now. what could i possible have?

A good checkup?: Perhaps you need to consider a good full medical exam and also a trial course of treatment with a psychotherapist who can help you wade through life situation possibilities that could be hiding in plain sight - or deeper in your mind. 3 years is enough time to spend hoping things will change on their own. Try to get this figured out before life gets even more demanding. Best wishes for a good life.

Sounds like stress: Stress can take many forms. Sleep disturbance is a common one. In fact the constellation of features. Commonly travel together. It would be worth consulting a psychologist. For help. There are many stress reduction techniques that can be taught.