Can i get pregnant on MIrena IUD?

Ive had the Mirena IUD since last October... since then I have had NO period or spotting what-so-ever.
I do have monthly breast pain, I usually take at least one test from the dollar store a month. The other reason why I am so concerned is when I went to my first check up after having it inserted my strings were missing and
my gyno brushed it off. She said the strings "coil" and it was not uncommon and quite normal for the strings
to flucuate in length or go missing throughout the month. This was contrary to all i've read on the internet i.e. "if your strings go missing or change in length call a doctor ASAP"

However, this month I am having symptoms ten times stronger than the other months. A little over a week ago I started having frequent urination and breast pain. I decided to take a test to be safe. On August 1st it was NEGATIVE. Still unconvinced I took a test the next day. It too was negative. However my symptoms were just getting stronger. My breasts really really hurt now, I've been nauseated, have had headaches, frequent urination, sleepyness..etc. and TODAY to boot.. I happened to feel something cold and noticed I my right breast was leaking something. NOT a lot, and it only came out when I pinched it (TMI, i know) but I freaked. AND I also noticed that I have gained around 10 lbs over night! I was feeling a little chubbier than usual but could not believe my eyes when I weighed myself. I haven't changed my diet or activity at all...  So now 8 days later I took another test and it was Negative. In total i've taken 6 tests in the past 8 days and they have all been negative. I am beyond freaked out. I made a GYNO apt but it's not for another 2 weeks. It is not a good time for my husband and me to have another baby. We were working at the same place and both were laid of. We are struggling o find other jobs, make our car/house payment and take care of our other 2 kids. It really would not be a good thing, plus from what I hear pregnancy with an IUD is usually not a good thing anyway. I'm terrified. I am probably going to see if I can get an apt with my general practioner sooner than two weeks just because I am so scared.

Husband seems to think that it's the horomones in the Mirena causing these crazy symptoms or that I have
a horomone imbalance. He says if my symptoms are as strong as I say they are, which they are, then it
would most likely have shown up in a pregnancy test already, if it is pregnancy related. However, this does not make me feel better.

Has anyone else experienced this? Or if this is not pregnancy what could it be? I'm so scared. I really do not want to be pregnant. :(