I think symptoms in both peri and post menopause can be similar and my endo told me to go by when in the cycle you feel the worst (where middle points to high oestrogen and either ends points to low oestrogen). I also don't have heavy periods, maybe just a bit more clotting on one day, and the only time I had painful breasts was when I was taking a oestrogen dominant pill back to back. My main symptoms were silent migraines, extreme nausea, anxiety, temp extremes (sometimes hot but mainly freezing cold and sometimes shaking), twitching face and leg muscles, brain fog, slow transit digestion and mood suddenly plummeting.
I always thought the oestrogen dominance thing was about xenoestrogens in the water supply and food chain which I've no idea about. In peri you can have oestrogen surges where it can go higher than anytime in a woman's life, one hypothesis being that eggs are running low so more oestrogen is needed to stimulate the follicles to produce one more (or it would be one in my case!) pregnancy.
I wonder if those who have it easier in peri already have lower oestrogen so levels stay normal but then have it go much lower post meno. (Or that may be just me just trying to make myself feel better that I'll have a lovely post meno)!