T.H.
I'm on my second Mirena and I love it. I think they are great and love not having periods! But it doesn't work smoothly for everyone…I truly feel that Mirena users either love it or hate it and get it removed within the first 3 months.
That being said, it's time to get my second one removed and I'm going to go off the hormones completely (even though it's a low dose). I'm pushing 40 and I think it's time after so many years on birth control. At 44, I honestly think you should consider the same.
I agree that an ablation would be something to consider. I know a few people who have had them and have said it wasn't a big deal, pretty easy recovery, and they are very happy.