Stress can affect your cycle and TTC, but I think most people would agree it has to be pretty extreme stress. Being anxious about ovulating or stressing over your charts are unlikely to be the kind of stress that would delay O. Stress from a major life disruption (moving, job change, death in the family, etc.) or illness would be more likely to affect your cycle, and even then, it doesn't always happen. I mean, think about it. Women in war-torn countries conceive babies all the time. If that's not getting pregnant during times of stress, I don't know what is.