AF is late

I'm still nursing my daughter; she will be 15months next week. AF returned when she was 5months old. It has been heavier since pre pregnancy, but still came regurlary. As of today AF is a full 2 weeks late, however all HPTs have been coming back negative.. I've been told that because I'm nursing that can cause a false negative, but idk how true that is. So, my question is, should I call the dr to try to schedule a blood test, or should I wait it out?