when do I count my last day of my period?

Destynee • PCOS • 2 natural born • pregnant with our letrozole baby🤍
A little TMI but I took my tampon out this morning and it barely had any blood and it hurt so bad because it was dry. So I haven't put one in all day and there's no blood on my panties. Do I count the last day of my period as yesterday or today?