Late af was it chemical pregnancy?

[scrunchy]

My period started 10 days late .
Yet 10 days ago I had cramping as if it was coming for 5 days.negative pregnancy tests
Only second period since givubg birth last year ,am still Breastfeeding.
Was it just late ? It's extremely heavy now ,or a chemical pregnancy ,as I'm mystified why the cramping 10days ago.its never in my life been this late before

My periods were all over the place when they started again after breastfeeding.

I've always had them like clockwork once they return ,it's my 4th baby ,they return usually 9months and then every 30days .