Pregnant or Hormonal changes?

My last "period" was May 5th (I have an IUD) on June 5th I spotted for a few hours with small cramps and then I was fine. Since then, my breast are non stop hurting, they look a little swollen and I've noticed my veins are starting to show more on my breast. Also my nipples are very sensitive and sometimes they hurt to the touch. I've also been having a lot of discharge. Sometimes egg whites sometimes watery. I took one pregnancy test around June 6th or 7th and it came back negative. I haven't had any nausea but I do have small pain down in my belly like where I suspect my uterus is. Can I be pregnant or have an hormonal disbalnce? Also I have been very moody and sleepy!!