Perhaps read up on endemetriosis and discuss it with your gp before you take a reduced dose? You will need regular scans. You seem to be worried about hrt so adding an unnecessary health risk may not be the best move.
I might have missed this (easily done as I tend to skim read!) but I don't think Jmargaret mentioned endometriosis

. As far as I know (and I stand to be corrected!) HRT does not cause this (although can exacerbate it with certain preparations) and if you had endometriosis you would probably have had it diagnosed when younger and would know you had it.
Thanks so much both Hurdity and stellajane. Im trying.
I may even start the progesterone tonight, sooner know the better!! Im.gonna maybe try 100mg of utro for the 12 days (vaginally too) - will this be ok? I know 200mg the licensed.dose but beibg vag would 100mg be ok? Sorry for more questions. You ladies are a godsend. X
Nevertheless - although research has shown the efficacy of a reduced dose of progesterone ( for a given dose of oestrogen) when used vaginally compared to orally - in keeping the womb lining thin - as sheila99 said you don't want to add unnecessary health risks just at the moment by going off-licence. The potential problems from insufficient progesterone could be endometrial hyperplasia resulting from over-thickened lining which can if untreated sometimes lead to cancer.
If this regime suits you - then depending on the bleed you get you might be able to reduce the dose of progesterone after discussion with your doc.
Anyway good luck with it - nothing wrong with a bit of placebo either - it helps part of the way!! The rest is down to the HRT!
Hurdity x