lactating.. not pregnant.

hello, about a month ago I noticed I was producing a small amount of colostrum. I have no children, but I have been pregnant before. me and my fiance have been trying since January. in April we decided to try pre-seed. I noticed about a week from when my period was due that I noticed the colostrum. I thought it might be a preg. symptom, but I got my period. So I stopped paying attention to the colostrum. now I'm around cycle day 15 , still using pre seed. And still have the colostrum and now my nipples hurt, and it cause my good around it to be sore as well. Has any one had this happen before? i don't think I'm pregnant, so I know that's not it. if you did have it and wasn't pregnant what was it? I do have an appointment for my obgyn, but she was all booked until next month so I am just curious!