3 days BMP

I have a silly question.. really trying to understand.

If I took a blood test before implantation, would it be accurate still?

Took a blood test this morning and just started spotting, not heavy enough to be my period (yet at least) but the test was negative 😔

I’m not supposed to get my period for three more days.

So is it my period that just started? Or implantation spotting?