CD 35, help!!

So today is CD 35 and still no AF. I've taken 5 tests within the past week, the last one being yesterday, Thursday. And all of them have been negative, not even a faint line. I've never had a cycle this long, the longest was 33 days once. I don't know when I should test again and when I should call the dr to get a blood test. AF was due either July 4th or 5th, so I'm almost a week late. Wouldn't I have had at least a faint line by now?