Confused.. can anyone explain

So my period is 11 days late..this never happened to me.i have a 28 days period that's always on time
I'v been ttc for 6 months and did my best last month so when it was late i expected this to be "the month"
But i took 3 tests the last one this morning and they were all BFN :( not even a faint line
Should i lose hope completely? 
Or do i need to get a blood test?