Hi Freda
Although progesterone has a sedative effect, in the doses taken for HRT and for progesterone intolerant women, it can have just the sort of effects you describe ie low mood and decreased energy - can also give rise to fatigue, foggy head, headaches etc. Taking it all the time ( I presume you were if you were on 100 mg) can mean you feel like this all the time.
These depressing effects are why several of us on here continue with a cycle well into post-menopause ( like myself at 61). The anxeity creeping back is due to the decreased oestrogen. Have you thought of taking it cyclically? If you are under a gyane if you can persuade them to let you try a slightly longer cycle then you would have the benefits of being on oestrogen only for linger each cycle. The disadvantage of this is that your body has to acclimaitse to the sudden increase in progesterone and then a decrease - progesterone withdrawal - which some women have problems with. If you took it cyclically if your doc was OK with it you could take a lower dose vaginally than orally - or for a shorter time in the month.
You can only try - and this is what I would suggest - definitely not progesterone all the time. If you are post-menopausal anyway this (without oestrogen) can lead to overthinning and in extreme cases ulceration of the uterus lining with subsequent bleeding or spotting.
Hope this helps!
Hurdity x