Mirena and ectopic pregnancy?

Alright, so I got my Mirena put in on Feb. 19th of this year. About two weeks previously I had been on my period, had sex unprotected after ending my period, but took plan b the next day. My period returned within 4 days. 6 days after that ended, I got my Mirena put in. Obviously they did a pregnancy test beforehand and it was negative. 
Shortly after my Mirena was placed, within 24 hours, I had sex with my boyfriend again. Since then, I have had spotting everyday. (Which I know can be normal with Mirena.) but for the past 4 days, it's heavier than spotting & lighter than my normal periods. My next period isn't for 10 days. I've researched symptoms for ectopic pregnancy and have found that I have had multiple including; severe cramps (waking me up), pain when having bowel movements, spotting coloration from brown to bright red, shoulder pain, and gastrointestinal like symptoms. 
I scheduled an appointment with my OB/gyn for next week.
But, what does everyone think? Am I just freaking out or is it highly possible?