Hello and welcome to the forum. I'm so sorry to hear that you have such fatigue and for so long. This sounds like it has been truly terrible for you. I'm assuming you have worked with a doctor to help diagnose any underlying cause? What types of tests have they done? I urge you to continue to work with your doctor and keep pushing for improvement of this.
Here is some general information about chronic fatigue syndrome. https://www.mayoclinic.org/diseases-conditions/chronic-fatigue-syndrome/symptoms-causes/syc-20360490. There are usually underlying things going on but in truth, they often don't know why someone has unexplained extreme tiredness. Working on various things may improve it though. Do you see anyone in terms of therapy? Are you taking any depression medication as it is so often very closely linked? Do you have much support in your life for the issue?
We're here to discuss this with you.
You can try to remove sugary drinks (soda, etc.), ice cream, sweetmeats, and all forms of crystallized sugar(in tea, coffee ) from the diet, which can effectively alleviate CFS for some people.