Mirena

I’ve had a Mirena IUD since June and stopped breastfeeding in December, had regular periods in Feb and April and now I’m 2 weeks late. The strings are still in place and no pregnancy symptoms other than I’ve been peeing constantly and I’ve gained 10 lbs in the last couple months but that could be quarantine related 😩. Is it normal for periods to be irregular or go away on an IUD? Anyone else with this experience?