Need advice

Ok so heres the thing my period was suppose to start on Tuesday ( usual it starts on the Tuesday and is light then Wednesday to Saturday it’s extremely heavy and then by Sunday / Monday it goes away) however it didn’t. So By Wednesday this week when I wiped after I pee’d there was nothing. I was curious so I put a tampon in and when I removed there was a light brown kinda colour on the tampon but very little. So today being Thursday I tested and I got a negative pregnancy test 😢😢 so still confused. I put a light tampon in just to air on the side of caution but yah so I’m not sure what is going on.

Any advice ??