10 day late period?

I miscarried in December, but everything has been normal since. I was calculated to start my period on 4/6, so far nothing. I took a test Thursday afternoon and it was as negative as could be. I have no signs of anything. I had the stomach flu the last week of March and for 11 days now, I’ve had an awful cold/flu. Body aches, fever, all of it. Should I keep testing? This has never happened to me before