Help!

I am going on 9 days of being late on my period.

My breasts aren't sore really, but i get occasional nausea and constantly feel full. i get cramps and back aches, like i'm about to start, but still haven't.

I tested on my 5th day of being late and it was negative, i also got a blood test day on my 5th day, and it was still negative.

Could i have possibly tested too early?

When should i test again?