Light pink, barely there period...

For the last week Glo has been predicting my period, and it would be on time but it hasn't showed up. Off and on again when I go to the bathroom there is a very light pink barely there strip on the toilet paper; this has never happened before. I'm not pregnant, as I'm a virgin but am trying to track my period closely as I'm getting married in January and will start the pill in November. What's up? Stress?