I know nothing about the patches, or HRT, but I do know that tamoxifen has a similar effect in some women and builds up the womb lining to the extent that periods (if you are still menstruating) can be horrific (mine was 500mls lost each period!) and there can be breakthrough bleeding for the post-menopause. It sounds so much like this is what is happening to you, as the ladies above have said...womb lining thickened. You must be more pushy with your surgery and demand to be seen, sadly this is how many have to be with their NHS treatment now...on the ball and pushy.
Sorry, just read the full thread which didn't show at first for some reason....I see that you are away right now, abroad. Yes, make the appointment now. Have you decided if to continue with the HRT meantime ?