What are the odds I am pregnant, my husband just got a vasectomy we used condoms and I am still nursing?

I had a baby 3 1/2 months ago and my husband got a vasectomy, we have used condoms all three times we have had intercourse since the birth of my son and I am also nursing, but I have been having all the same early symptoms as I had with my last pregnancy, like nausea, moody, gassy, frequent urination, dizziness, weight loss and lake of appetite. What are the chances I could be pregnant with all these precautions?