My period is late and hpt are negative

So my period is 9 days late! O don't feel like it'll be here tomorrow since I'm not experiencing any symptoms related to pms. I took 3 hpt and they are were negative. All were the dollar store brand. I haven't been late for a period since i was 21 and I'm 30! I know that stress can play a role but even when I'm stressed it comes. What should i do next??