Ovulation test

Kristen
I'm new to trying ovulation tests and took one on Wednesday and there was a faint line. I took on Thursday night and it was clearly negative (no faint lines at all). Took on today (Friday) and no faint lines either. I am day 13 today since the start of my last period. I've been tracking my bbt and it had a small spike this morning but cm is still creamy. 
Did I miss my window??