Pregnant with my iud?

So I’ve had my mirena for about a year and a half now and I have never had a problem with it. My periods stopped after about 8 months. So I never really know when I’m suppose to be having my period. But about 2 weeks ago my boobs started to hurt really bad. And I’ve been nauseous through the day at random times. My boyfriend and I have unprotected sex and I’m kinda scared I’m pregnant. I took a test and it came back negative but I’m still on the edge that I might be. Am I just over reacting or should I go see a doctor?? Please help!