Answers??? Can anyone help?

I have been very loyal this app😄.and has been really accurate since I started...glow said aunt flo was suppose to start on the 6th and I have yet to even spot and today is the 11th?and I don't have any pre aunt flo symptoms... I've taken a test but it was negative..😢.??!!?? Should I go to the clinic? My period has never been this late.but the test was negative!!???!..any thoughts would help thanks guys 😊