Hi Deborah, my understanding is that a certain percentage of women have no bleed on sequi HRT. 15% from memory - but don't quote me on that - memory is rubbish & I can't find the source of that stat today.
I'm postmeno like you & found I had no withdrawal bleed for nearly a year on a far lower dose of Provera than you & for only 7 days pcm, admittedly with only a low dose patch. Then eventually had very slight spotting one month, so scanned to check all was OK & found lining was only 1-2mm with no abnormalities. So the Provera had been adequate to thin whatever buildup I got from the oestradiol. Bloods showed I was absorbing the oestradiol well - getting twice as much from the low dose patch as I previously got from a different brand patch of double the dose. But postmeno, with no ovaries & very skinny I won't have been producing much oestrogen of my own & if you are postmeno you should be in a similar situation in terms of minimal endogenous oestrogen.
Not until we increased my dose of oestradiol did I begin to get withdrawal bleeds on the same minimal dose of Provera.
I think the synthetic prog variants like Provera & Norethisterone can be very efficient. So my guess is your Provera dose is working very well for you. Alternatively, you may not be absorbing the Sandrena sufficiently to build the lining much. As you say
so far so good
I take it your symptoms are well controlled, suggesting you are getting as much oestrogen as you need? So the poor absorption suggestion seems less likely.
Do you have any gut feeling for what might be happening? You could maybe ask whoever manages your HRT about scanning for reassurance.
Wx