I started HRT 13 yrs ago. Pre-op, I never felt tired. Post-op, as my T levels dropped further, to low/under normal female range, I felt I didn't quite have the energy/stamina I used to have and this significantly affected my quality of life. Just recently, I started taking a small amount of testosterone and my energy is better. I feel more 'me' again.
Your symptoms may be temporary as you adjust to the change in sex hormones but if they persist, you may wish to discuss the issue of too low T with your doctor.