Hi lizzog - when you say your Mirena has ‘one year left', how long has it been in place? For HRT purposes it should only be in for 4 years before changing it ( 5 years or more before menopause), and maybe it's run out of progesterone and this might mean that the womb lining is building up and would explain the heavy bleeding. Before meno hits and in early peri meno you are still producing some progesterone yourself so if the Mirena it just used for contraceptive purposes, then when it runs out of progesterone this won't matter. However, if you aren't producing any progesterone (I suspect you're deeper into meno now so not producing progesterone) then you need it changed at least every 4 years. IF it's been in 4 years then I'd pop to the doctor have a new one inserted.
Mirena will Oestrogel is a great HRT combo and if it has suited you to date then I would continue with this. DG x