Hi
Firstly, the Mirena may be in place - the strings sometimes break. It could have dropped out but the scan is a good idea and you could have another fitted. If it has gone up further then they will need to remove this but I can't tell you how
Secondly, you can just stop the oestrogen. You are young so some oestrogen is advisable till at least 50 to protect your heart and bones for the long term.
As for the blood pressure - hog blood pressure is not a reason for stopping HRT. Medication can be given o control blood pressure but changes in lifestyle would be your best first option.
If you are carrying too much weight, don't exercise etc then these things need to be addressed - not just for the blood pressure but for your long term Health.
Eat regular small, highly nutritious meals with less fat and sugar/carbs and try to do more exercise eg brisk walking, dance classes etc. DG x