Help please I stopped midpack.

Hello everyone, 

I am new to this site and I've seen very great threads and helpful answers. I was hoping someone can help me understand my situation. I have always been on a 28 day cycle and the last reg. cycle was from Aug. 11-14th but I stopped the BC  10 days later. I had some bleeding Sept.1-4 and I counted that as a reg. period. But from what I have been reading it may have been withdrawal blood. I've tracked my period on an app and since I counted the Sept 1-4 as a reg. period it says I'm 4 days late but I'm not sure if I should try a P test? Can someone please help me sort this out?

Thank you so much!!