Pregnant?

I have the Mirena IUD. but I was having weird cramps for about a week, and checked the strings of my IUD and could not feel them (and I haven't checked them since). About 5 days into the weird cramps, my SO and I had unprotected sex and he came inside me. Lately my nipples have been very sensitive, and I have been having a crazy craving for milk (I had 4 big glasses of milk last night). Do we think there's a chance I'm pregnant??