copper coil - really long periods

[flootshoot]

I've had the copper coil in for about 2 years. Prior to having it I had short cycles (approx 25 days although anything between 23 and 28 was normal for me) and really short light periods (3 days) My periods were heavier and longer (6-7 days) after it was fitted which I was expecting. But the last few have gone back to being lighter. I've just finished one which was not particularly heavy but checking on the calendar it lasted nine days! I checked this morning and I could feel one string. Does this sound normal? With such long periods and short cycles I feel like I'm never off!