Hello Sunriser,
Chronic fatigue can be a number of things. I assume blood tests covered auto immune disease checks, as well as thyroid check too? These are the obvious that spring to my mind along with ME and chronic fatigue syndrome. Am sure others will be along with advice and experiences. Stress and anxiety can also bring on fatigue, but it may simply be linked also with your hrt which may need tweaking.
I would recommend you get fully prepared for your appt, maybe do a bit of a daily symptom diary to see if you can see a pattern from day to day. And write down any symptom that affects you, and a list of questions you want to go through.
Sorry not to be able to help you further, I am not trying to scare you with a false diagnosis - am not medically trained obviously ! But do tell the consultant exactly how you feel and how much it affects you.