Definitely a meno symptom but can't say if it's because your hrt needs tweaking or not
I go through flares of crippling crushing fatigue where I just can't get my act together, I function for the must dos, like work and babysitting but cannot think beyond that. I live for the moment I can rest again. I did change hrt and have to say things are really improved, I still get tired but seem to have to ability to push myself now. So I guess in a way your regime may need a tweak.
Incidentally, my new hrt converts whatever ratio it desires to oestrogen, progesterone and testosterone so the added benefit of testosterone properties could well be what is helping me x