Tiredness/exhaustion is not one of oestrogen's side effects - it has the opposite effect. It is progesterone that has a sedative effect that can lead to tiredness, fatigue and depression at worst.
How long ago did you have your hysterectomy and did you keep your ovaries? Depending on how long ago - and if it was total + ovaries - your body will have been put into shock and hormones would be suddenly depleted. From what I understand this continues to become apparent for some time after the operation.
Do hope the oestrogen works soon so that you gradually feel better and less tired. If no ovaries then you may need testosterone as well.
Hopefully one of the hyster women will be along to help
Hurdity x