Mirena coil for womb thickening problems

[cashmerecardigans]

I have just turned 50 and have had problems recently with a thickened womb lining, causing ongoing bleeding. This resulted in a hysteroscopy to (thankfully) rule out anything more serious, but they have fitted a Mirena coil to balance out the hormones. I was advise this was better than taking progesterone tablets as the hormone would not need to pass through my system.Previously I had a copper coil, which was fine. The Mirena has been in about 7 weeks now and I am noticing a few things - firstly some weight gain (about 5 pounds), which I can't put down to anything in particular and secondly an increase in bra size and very tender breasts at times.
I am now a bit worried whether I've done the right thing, as it's a lot of weight to gain in a short time. I don't know whether anyone else has experience of this? I'm not sure whether to go back and ask fro the tablets instead, but not sure if this would have the same effect or just put up with it until the menopause arrives?