Help...TMI

Ok sooooo my period is 2 almost 3 weeks late(which is kinda nornal...like they're never on a regular cycle even when I was on BC..but they've never been THIS late) I took a test last week which was negative. The day after I took the test I got what I thought was the start of my period(light brownish spotting..I usually don't get that until my period is done) then it went away for a day and then started up again but this time it was REALLY dark brown and had the little clots in it with a tiny bit of red. So I thought maybe that was my period. Nope wore a tampon for 10 hrs and it came out clean. Then the same thing happened for the next 3 days. I'm super confused on what is going on bc I've never had this happened before and my leriod has never been this late. I read online it can be anything from just the old blood coming out instead of your period to hormone imbalance to PCOS to early signs of pregnancy yo missed miscarriage to a problem with your reproductive system. Has anybody ever had this happen and if so what was the end result or reason for it? I'm waiting for my tricare to transfer over so I can go see a doctor but just curious if this has happened to anybody else. I can't help but feeling like something is wrong....