I can only go on my own experience ladybird, I had a hysterectomy and kept my ovaries and cervix, I have only ever been prescribed estrogen only since the op, and have had no problems, I have had different delivery methods over the years but no doctor has ever suggested I needed progestin/progestin to protect a non existent womb. It might be possible that the cervix may retain some cells to cause a few drops of blood, some women can have this, and you may have a little discharge for a while after the operation, its only been four weeks since you had your hyst.
I sometimes had this and reported it to my doctor and she said it was perfectly normal and never suggested combined HRT and it eventually petered out.
I do use an OTC natural progesterone cream sometimes, it helps to calm and can aid sleep.
I continued having my smear test when called too, they always came back normal.
Your main concerns are night sweats that estrogen will certainly take care of, combined will too but may come with the problems that prescribed progestin/progesterone can bring, that's one of the good things about hysterectomy not having to use these if you don't want to.
