Missed period! Need some advice

So I’m currently 11+ days late on period. According to this app, I was suppose to start my period in May between the 23rd/24th but I didn’t. I’ve been thinking about what I did different that would probably throw my period off. And here lately nothing has changed in my day to day things are still the same. Plus my husband had a vasectomy in October of last year so I highly doubt I can get pregnant. I’m trying not to overthink or stress about it but I’m worried because I’m super late and all my tests are negative.