so I have a question..

So me and my boyfriend practice safe sex like 90% of the time. I'm not on any birthcontrol. But I watch my cycle and everything very closely with this app.
I'm 9 days late on my period, an no sign of it coming. I've taking a test an it said negative. But I took it 3 days after my period was suppose to come. Has this happen to any of you. An should I take another one an see what that says?
An what sucks is my obgyn that I know an go to and trust. He moved to the east coast an now I have to do dr research for a new one.