All month spotting

Has anyone ever had spotting that pretty much lasted all month? I have really regular periods, but ever since I got off of birth control in May, I literally spot the entire month except during my fertile week. Has anyone else had this problem and found out what it was? I have a doctor appointment soon, but I was just wondering. It's really annoying, plus my SO and I are trying for a baby. I feel like this is because of a problem that won't let me get pregnant.