Hi mcwey
Isn't is annoying when they don't explain things properly - they should, if for no other reason than to reassure us. All this terminology can seem so frightening.
Now I'm certainly no expert but I am pretty sure that annovulatory cycles happen during the peri meno stage when, some months, we don't ovulate and therefore the womb lining builds up too much and might the cause of the fibroids and possible erratic and/or heavy bleeding. So endometrial hypertrophy would probably refer to this thickening the the lining - hence the need for the D&C. Hopefully someone will be along with more medical knowledge who can say whether I got this right or not. The Mirena will reduce and stop this over thickening and will usually shrink and/or prevent further fibroids from happening.
I had this problem happen in my mid 30s and like you I had a D&C done which resulted in my periods stopping - they then did blood tests which showed I was in peri meno.
From what you are telling us you are getting very good treatment and advice so I don't think you have anything to worry about and the possibility of further investigations would just be precautionary. 25 years ago when I was in my 30s, they didn't use the Mirena for controlling meno problems and if this is helping you then that is great.
Delighted to hear you are feeling better - stop worrying and enjoy life. Dg xxx