Hi Sues
I too have had a hysterectomy, retaining my ovaries. Before perimenopause, I had oestrogen dominance and took progesterone cream and found it very effective in improving my mood. I had the hysterectomy at the start of peri and insisted on continuing with the progesterone as I felt it improved my mood (I have tried various forms of oestrogen too, still trying to find the right one). It's been 6 years since the op and I still use progesterone 100mg (bio-identical), I prefer the tablet to the cream as you can develop a tolerance where you apply the cream, so if using make sure you apply it to as many different areas as possible, I found this out the hard way. I have a good GP, she doesn't see any harm in me continuing on progesterone if it makes me feel better.
I definitely believe there is more to progesterone. I asked my menopause psychologist about it and she agrees that progesterone is good for me, it effects the brain and stomach, so I don't think there's anything wrong with taking it despite not having a uterus. Try it and see if it works for you, there's no harm.