Period due today but very mild bleeding

I calculated my ovulation and had intercourse on the 12th, 14th and 15th day, including date of ovulation. Today would be my first day of my next period, but there hasn't been regular bleeding. There was a brownish discharge, and then maybe a teaspoon full of regular blood (if at all, from what I could tell), and now there seems to be none, or very very mild discharge. Today would also be my 13th day post ovulation.

Could I be pregnant?

I am trying to conceive, and am anxious!