Thanks for the query.
develops in approximately 20% of Mirena users by one year. The possibility of pregnancy
should be considered if menstruation
does not occur within six weeks of the onset of previous menstruation. Once pregnancy has been excluded, repeated pregnancy tests are generally not necessary in amenorrheic women unless indicated, for example, by other signs of pregnancy or by pelvic pain
I recommend you to get a USG done to rule out pregnancy esp ectopic pregnancy.
Report immediately to a doctor immediately.
hope this helps,