am I pregnant? please help!

So I have had my iud since August. I have had sex many many times. I've only let him finish inside a few times. And after the first time I took the morning after pill and after the other 2 I didn't. But I have mirena and I trust it. I've been having cramps and my breasts have been achy and nipples have been tingly. And I have had a huge increase in acne. But I have started my period. I took two tests right before I started my period. And both said negative. Then I took one today and it was not clear as to if it was pos or neg. But I have now been bleeding for about 15 days now.  I just don't understand. My iud is 99.9% effective and I've been on my period and the tests have been negative. Why am I having all of these crazy symptoms all of a sudden?