I think you're another victim of the 'everyone is meno by 54' culture. You're having regular periods but they put you on a conti regime - it would be more surprising if you DIDN'T bleed. As your symptoms returned you need a higher dose of oestrogen not a conti regime which is the same dose. Evorel sequi and conti only come in one strngth so you may have to change hrt. Most likely the scan showed a thickened lining as you haven't been shedding properly due to the conti regime.
I have been a victim of it too recently. As above, it seems it always goes on the 2 week pathway and there seems to me to be unnecessary panic about it. You can ask for a phone appointment first (I did) to give you an opportunity to ask questions. The person doing the scan refused to give me any information at all, my gp told me thickened lining, 2.5mm too thick (though after 8 weeks with no bleed on sequi imo surprisingly thin and nowhere near dangerous). It seems 'unexpected bleeding' had been added too. This was because I told them I had 3 of my own periods last year - which, as all medics know, is completely impossible as I was over 54. They even told me if I was 10 years younger at the same stage of meno (probably had my last bleed but not 1 year yet) they wouldn't have done anything. My biopsy came back clear, I'm sure yours will too.
Perhaps you could ask your gp how she thinks a conti regime on the same oestrogen dose is going to prevent symptoms of oestrogen deficiency? And why she isn't increasing you oestrogen which will aleve the symptoms?