Hallow Dear, Mirena is an intrauterine contraceptive device that is impregnated with a hormone called as Progesterone. This Progesterone can delay the menses. In fact while postponing the menses also, Progesterone tablets are given. Your symptoms of nausea & vomiting cannot be attributed to pregnancy as it is hardly one day that you have missed your period. These symptoms, including frequency of urination appear 10-15 days after missed period. Progesterone can give rise to nausea and vomiting. It takes more than 15 days for the breast symptoms to appear after the missed period; however, Progesterone is known to cause breast tenderness and little engorgement. I would attribute all your symptoms to the Progesterone release from Mirena. You should get your menses shortly. If you do not get them for next one week, then you may try urine pregnancy test and/or ultrasonography done for detection of pregnancy. However, the success rate of Mirena is very good. I do not think you could be pregnant. I hope you are satisfied with the answer.