IUD HELP!

Kaylee
I have had an IUD for about 2 months, and my boyfriend and I were sexually active during the second month. The last time we had sex was the 11th this month. The first time we had sex was on the 4th this month. Each time he wore a conform and said none of them broke.   
I had tender breast a after the first time we had sex and I am due to have my period, having slight cramping, dizziness, tender breasts, fatigue. I didn't know if this is period talk or not. I took 3 tests on the 22 this month and all were negative. We're the tests still early? Do you think I could be pregnant?