What Could Breast Milk Production While On Implanon Indicate?

I am on implanon birth control and i can express breast milk. I have been on implanon for three years in may i had a child in 2011 and this recently happened. Is it possible that i could be pregnant on implanon? I have taken pregnancy test in the past all negative i dnt have regular periods because of my birth control so i wouldn't know by a missed period. Could a blood test tell me if i am pregnant? What could cause breast milk production?