Worried my wife may be pregnant on IUD?

My wife has been on the Mirena Iud for a year now. She got if after she had our son. She also exclusively breast feeds, and he is on solids as well so it is not as much breast feeding. Lately she has been having a lot of discharge. Very watery. More than usual. She has no itching, no smells, and sex is normal, so we are not sure what this could be caused by. The last two days she said she woke up feeling nauseated. We had sex last night and everything was fine. She washed up after words and in the middle of the night woke up because she had so much discharge. We figure it was from me, but after using the bathroom, she noticed a tiny streak of blood in her discharge. This morning she woke up, and had more discharge streaked with pink blood. Does this sound like pregnancy? She had something similar when she found out she was pregnant with our first. We are taking a test today, but she wants to prepare her self. She hasnt had any bleeding except right after she gave birth. Thanks and God bless!