Am I preg?

I am now 4 days late and have tested with first response preg test  day 3 of required period but it was  negative.
I am always on time and had unprotected sex the last day of my fertile window (7 days before period was due) 
I have a soree lower and upper back 
I am light headed 
Shortness of breath 
Could this test of been taken to early, anyone have a Simalar situation