Weird period

So af started Sunday morning and it's been really weird. Way lighter then usual and I haven't had any cramps. Today I haven't bled at all. That's like a 2 day light period which is very unusual for me! Usually I last 4-6 days and it's a medium flow. I took a test Saturday and it was negative so I know I'm not pregnant but I don't know when I ovulated. Could stress cause my period to be so weird? Only thing I can think of.