16DPO but BFN?

Hi everyone... Glow said I was supposed to have my period on Tuesday but I still haven't had anything-5 days late. I am normally about a 27 day cycle and the longest I've ever had is 29. I am now on day 30... Been very tired and grumpy the last couple of weeks. Took a test yesterday and not even a faint line. Is it possible I'm pregnant and it's just not showing up on the tests yet? How long before I test again? Thanks!!