OPK question.

I took an ovulation test yesterday n it said no but we BD anyway. Have every other day lol.  I took one today and it only had one line? It's never done that before. My dr said I should ovulate this morning. She's been having me track everything for the past couple of months and based on that is how she got my ovulation. So my question is can I be pregnant and the ovulation test just show one line? Sorry to sound like I'm stupid but this is my first month doing the opk.