My Husband And I Have Been Trying For Baby #1

My husband and I have been trying for baby #1 for 4 months. My periods have always been regular and I'm tracking and charting BBT and cervical mucus. My period isn't due for another 2 weeks, but today when I wiped, I had brown/orangey spotting. It only lasted for an hour or so. This has never happened before. I'm cycle day 12 and still no positive ovulation test. What could this mean?