Ob-Gyn questions? Ask a gynecologist online.
This is Dr. David
it sounds like you are having bad breakthrough bleeding after having your mirena placed and not having a period for a year.
this can happen and can be 100% normal.
after a year of no period, the uterine lining can build up and can come out with a heavy period.
you should see a doctor and get your hemoglobin levels and ferritin and iron levels checked again.
you could be getting close to perimenopausal state as well
let me know if you have questions.