Hi Moonshine - you will have some idea of how near you are to menopause depending on what your cycles were doing prior to starting HRT, and how long you have been on this regime. If you are nearing menopause or post then you might benefit from a longer cycle - ie instead of taking Utrogestan for 12 out of every 28 days then, you can stretch it a bit - firstly to every calendar month and then maybe a bit longer - which will limit the time you are on progesterone. Also this mught depend too on what sort of bleeds you get currently. If very heavy then stretching the cycle won't work or rather might give you heavier bleeds. However taking vaginally should make the prog more effective...
Alternatively as the others have suggested you could take it vaginally to minimise the side effects while taking it, or take a daily dose of 100 mg as Dotty says - if you are not yet post-menopause or very near then this won't work as you'll get your own cycle coming through and random bleeds.
Hurdity x