Random bleeding?

Back story...

I was 3 weeks late for my period before it finally showed (or so I thought) it lasted for 7 days and it was just when I wiped! I just thought it was a light period! All tests were negative too! I logged it into glow and left it. Fast forward to the next period glow tells me I’m 2 weeks late! Then I had spotting on Friday just gone so thought oh it’s coming and this is all I’m getting since? Not enough to put a tampon or liner in and it’s never in my underwear only when I wipe again? What could this be? Before this my periods were every month without fail and would last 5 days with little clots. I can’t get a test until Thursday as I’m on holiday! But surely the test would have showed up when I was last spotting? ( I was taking them for about 3 weeks straight)