Hello, and I hope I can help you today. If your Mirena IUD has been inserted within five years, you really do not need to worry about pregnancy as the IUD remains effective no matter what kind of bleeding pattern you have. The Mirena IUD does not affect your normal cycling of your hormones, so even if you are not bleeding at the correct time, you still may have hormonal symptoms associated with both ovulation and the correct time when your menstrual period should occur. Furthermore, pregnancy symptoms can vary widely between women, and feelings like breast tenderness, nipple soreness, bloating, nausea, spotting, and mood changes can be associated with premenstrual symptoms as well is pregnancy. Therefore, if your pregnancy test was negative, it is nearly impossible for you to be pregnant. It is true that urine pregnancy test will be positive within 2 to 3 weeks of conception, so if you really are concerned you may repeat the test in another two weeks. However, again, the Mirena IUD is nearly 100 percent effective if it is in place and has been in your body for less than five years. At five years, it is recommended that you see your health care provider and get your IUD replaced if contraception is still desired. I hope that I was able to adequately answer your question today, and that my advice was reassuring. Best wishes, Dr. Brown