Today: 3 days late

Was suppose to start on the 15th but haven't ... Last month i was almost 6 weeks late but i started bleeding on the 6th week mark ... Maybe im back to irregular again :/ Thursday it says im suppose to start bleeding according to this app but thats also a day im going to the bar to see Jason Michael Carroll with my future sister in law and she wants to get me wasted and Im not sure what is going on so if anyone thinks I should wait a few to take a test or see if ill start bleeding on Thursday