What about diet & Sleep patterns? I dont know if it has any effect on HRT, but making some dietary adjustments can make a big difference! I used to be soooo lethargic, but since I cut out Dairy & Gluten and amped up on superfoods (kale, goji berries, Cacao (especially cacao) i'm more awake and sharper than ever! Also try adjusting your sleep patterns to 10pm - 5/6am. Sounds weird but our bodies were originally designed to rise and drop with the sun. Modern technology has changed that, and we've somewhat adapted, but some people are more sensitive than others. HRT might just be making you more sensitive to these things?
I dont know if it will work, but all I can say is these things really really improved my quality of life, and they may help with your fatique. Worst case, you'll just be living healthier, nothing wrong with that 🙂 (FYI, took me about 2 weeks to start to notice changes. Now i'm addicted to that sleep schedule)