Missed my whole period!

I had normal periods before this one. I’m 22, breastfeeding a 2 year old, I am stressed I could say that, but the only time I’ve ever been so late is when I was pregnant. The tests keep coming back negative, and I’ve been feeling cramps for a week now. How likely can “stress” be the cause for my missed period? I’ve been stressed before in life it never affected my cycle... idk what to think.

Update: yeah my period came a whole 8 days later