Not normal

Ok so two months ago me and my hubby tried for a baby. I got my AF that month in December but it was light and than AF Came in jan and it was light. My AF was due 3 days ago and we haven't tried since dec for a  baby. My cycles are always on time and normal. Can you still have a period and be pregnant? I did a test i. Dec that was a very weak positive. Am I going nuts ??