Pregnant or overthinking?

Dre

I had my last period August 5,6 and 7th and just got another one on Monday. Exactly 2 weeks from my first one. With it I’ve had cramps and bad nausea. I’ve read stuff about implantation bleeding and stuff because it’s super weird I’m having a “period” again. I took a pregnancy test just to be safe and it came up negative but I’m nervous because I don’t know if it is a small period or something or if I’m pregnant. Anyone with knowledge of this please help!