A little nervous....

So im a virgin but my boyfriend and I "experiment"...he had fingered me and them rubbed his penis on my clit. He said he was careful to stay at the top of my clit. He cummed on me. Now this app says i should have started on the 31st of July and its the 3rd of august now. I deleted the scheduled period on this app and now it says i should start on the 7th of august??? Advise please? Is the app wrong or is my period late?