need advice.

so i had sex on july 29 w no protection but the guy said he didn’t cum in me but i swallowed it (lol) but anyways i got my period the first week of august (1-5) and on this app and the FLO app it keeps saying ill get my second period on the end of august and some on september but i never got it and now i’m 3 days late but i noticed that each month i had my period on different days . does this mean anything ???