How do I know when my period has officially ended?

I understand it sounds a bit unusual but I can never really tell when my period has ended.

I generally bleed fully(?) for around a week but as I get closer to the end of my period, the blood thickens and turn a brown colour. It is still too much to just be discharge but does it still count as my period?

I'm trying to work out ovulation days and the such but I don't know when to expect my period.