Late period

I haven't had sex since early July; I was taking the pill at the time, had two IUDs expelled in August, and then went to the ring for one week after that, but I'm currently not on BC. This app is saying my period is 6 days late, and I'm getting really concerned as to why. I've heard that stress can knock your hormones out of balance, but how much stress is "enough" to do that? Has the rapid change of birth control (and then early discontinuation) knocked it off track? I'm so worried that I'm making myself sick over it, and I just really need opinions/advice/explanations right now.