Missed period

Courtney
Okay so I was suppose to have my period on the 5th. I hadn't had sex in about 3-4 months until the 10th, but I was extremely safe. So even before I had sex I missed my period. Note: I came off birth control about 3 months ago. Would this be because of my birth control or stress or what? I'm extremely confused. Never thought I would miss my period so much 😭😭