Does hormonal coil (IUS) cause irregular periods?

The insertion wasn't as bad as I expected, it was very quick and the pain was manageable. I got it about 5 months ago and my periods are now very light but last around two weeks but I understand that they should shorten. I came off the combined pill (on which I took no pill breaks) just before I got the coil so am unsure which side effects (mood swings, migraines) are due to the coil or just because I now have a natural cycle.

I had my first Mirena fitted after the birth of my second child. It seemed to work well although my periods became even more irregular than then they were before and I had weeks of spotting at a time especially as I was approaching the 5 year mark. However overall I was satisfied and opted to have it replaced when it expired. This was quite traumatic and took a very long time as the strings had moved making it hard to access. However, the GP was able to remove it and I had a second one fitted which worked much like the first one. However, when it came time to have that one removed and a third one fitted my cervix went into spasm at the point of fitting the new one which was extremely painful and after what felt like forever the GP told me they were unable to fit a new coil that day and to come back. I went back and tried again a month later and the same thing happened. A month after that I was admitted to hospital with an abscess in my fallopian tube caused by repeated failed attempts to insert the coil. I was in hospital for 4 days and off work for over 3 weeks due to the pain/side effects of the antibiotics I had to take.

I started it after changing from the copper coil. Having previously had no issues with the mirena coil i thought this would be fine but instead i got constant spotting, bled after sex, had a painful and irritated cervix and lost my sex drive.