Chemical pregnancy?

Just looking for some others experience on chemical pregnancy…how do you know? I started spotted 7PO and I thought it was implantation bleeding, but it keeps going for 5 days and then today I got my period but it’s 3 days early which is very odd for me. I had really bad cramping this morning but that passed. I took a test yesterday and it was negative so I’m not really sure what happened, but it seemed so odd for me to spot lightly 5 days before period and then it came 3 days early…