Hello Machair,
My periods stopped on a regular basis a couple of weeks before I was 53, and I had four more periods spread out over two years after that and have now been period free for about a year. I continued to have PMT symptoms regularly throughout this time, though I started to see them more as symptoms of menopause that just got worse at times on a cyclical basis as my hormones continued to fluctuate, though occasionally I did have a period. I started to get flushes and palpitations sometime after my periods became irregular but it was low mood and anxiety that hit me hardest, and unlike PMT these moods didn't lift significantly as they would have done after a period and became an underlying constant. After 18 months I asked to try HRT and was put on Everol Conti patches, but even then I was still aware of my own cycle continuing underneath and would still feel definite PMT like symptoms. The HRT helped take the edge off my low mood and anxiety, but only slightly, they make it just about bearable, but only just, though they do work very well in helping me sleep for much longer, I used to only get 4-5 hours and now its around 7. I also used to get bouts of sciatica and that too appears to have cleared up.
It has been 3 years since my periods first started to become irregular and as I said I have been period free for a year now. I have noticed that over the past few months I don't seem to have had a strong sense of what my own cycle is doing any more; I used to know when I was mid-cycle for instance, because of a thicker vaginal discharge. So I am hoping my hormones are starting to level out and even my low moods seem less intrusive than before.
So going on my experience, and of course everyone's will be different, my PMT like symptoms have stayed with me for 3 years so far, but are starting to lessen. So going on what you have said I think your hormones are doing something similar and may continue to do so for some time, but nothing out of the ordinary for menopause. Hopefully you will not develop any other symptoms, but HRT is something to think about if you do, though it was not a miracle cure for me, just helped a bit.
Hope that's a little reassuring. It does sound like a typical part of going through menopause.