OPK confusion?

3 days ago, in the morning I took an OPK and it was very dark and VERY close to being positive, I took one again the afternoon and one again before I went to bed and they were both very negative. They have been clearly negative since and I'm wondering if I should count the darkest one as my positive and maybe I just missed my surge or whether I just didn't ovulate this month. I'm exclusively breastfeeding my 7 month DS and have had 2 cycles since he's been born so it's a little hard to pin point ovulation. Thoughts?