Hi there
This article about the peri-menopause explains what happens to the body, ovaries, hormones etc during the menopause transition:
http://www.menopausematters.co.uk/article-perils-of-the-perimenopause.phpThe fact that you are still experiencing pms symptoms implies that you still have some progesterone which would mean the ovaries are still working - but perhaps not producing enough oestrogen to cause a bleed. I don't know enough about this to comment properly though!
Oestrogen levels continue to fall for a couple of years or so following the last period, until they reach their all time low, where they stay. For many women, some symptoms begin at this time such as the effect of oestrogen deficiency on the bladder and vagina - leading to problems in this area, and there are other long term consequences of oestrogen deficiency - some of which are still being discussed and researched. Reduction in bone density which can lead to osteporosis is one such. Also effects on heart and circulation.
You shouldn't experience any pms at all once you are post-menopausal and your hormone levels are stable, and sooner than two years because you will not be producing progesterone - which is the likely cause of the pms you describe.
If your oestrogen levels are fluctuating, you may also notice this, and the fall in oestrogen contributes to some pms - but usually in relation to low mood. I would have throught the bloating, muscle tension and back pain are caused by the fluctuating progesterone - but I'm not sure it's easy to pinpoint the exact cause in individual women! Once you no longer produce progesterone these feelings should go but you may well experience the effects of low oestrogen as above (sweats, flushes etc).
There was mention of what happens when you stop HRT - this has been discussed many times and quite a lot recently. Go to the home page of the forum and do a search and this should bring up lots of threads.
The short answer is you don't know what will happen when you eventually stop HRT. What you can be certain of, is that you will not go through a prolonged period of fluctuating hormones! Oestrogen will just decrease until it is low again. You may experience hot flushes, or you may not. If you do, they may decline after a few months, or if you are unlucky they may go on for years ( just as they can do in women who do not take HRT).
This is not a reason not to take HRT though - as it is the quality of life while younger, which most women feel they need to prioritise - not worrying about what happens later.
Bit of a ramble again!
Hurdity x