Firstly, I am so very sorry to hear about what happened to your boyfriend, that is absolutely awful, I'm really sorry :(
If you take a test on the day after your period was due, you may not have had enough of the prgnancy hormone in your urine for it to show a positive result. I would take another test in a couple of days.
Stress can certainly play a roll on your menstrual cycle too, so just repeat the test in a couple of days to confirm.