I.G.
About 20% of women on Mirena will stop getting a period. An even larger percentage will experience very light and short periods. I stopped getting a period about 2 years into it and love it.
Most ectopic pregancies will show up in a home pregancy test, actually most ectopics are discovered because there is a positive test, but no embryo in the uterus.
But if you are concerned, yes, you should consult a doctor.
Good luck!