My own cycle would override utrogestan and any other progesterone as if they didn't exist, while I was definitely post meno.
What I did was just take utrogestan until I started to bleed, then stop. If it was a really short time, like 5 days, then I tried taking them after my bleed would finish as well, but that meant two bleeds a month, mine and the HRT one as well, even my GP agreed that was no good.
I don't have the answer, but you aren't alone. I've given up that merry go round and gone back to tibolone, I love good old tibolone and I have periods on it, every month, post menopause, how weird is that?
My personal opinion is that if you bleed some of the time, then you're ok, it's not building up, but I'm a nobody, don't listen to me!