I have an incredibly regular period, like exact at 29 day cycle and bleeding always starts between 6 and 8 AM and only ever lasts 4 days. I never cramp (the one time I did I went to the hospital because I thought my appendix had burst), and I don't actually experience too wild of mood shifts.

But... My last bleeding was only for 2 days. I took a test then and it came out negative and i was like okay I'm just really stressed out (my older brother died by suuicide in April so yeah stress would account for something). But I am actually 2 days late now and the test still came out negative. It was a super cheap brand test so I'm a little concerned that I am actually pregnant.