Does stress make your period super late? I'm 2 weeks late!

I'm 20 y/o and 3 weeks ago I was really stressed because i had a lot of exams and projects. I was supposed to get my period 15 days ago and I'm really scared I could be pregnant. Of course I'm still stressed for the same reason (my period being late!!) 3 days before my period was supposed to start, i did a blood test to see if I was pregnant and it was negative. Is it possible that stress can have a lot of impact?