Late Period, Unprotected sex, Negative tests


My husband and I have had quite a bit of unprotected sex since my last period. When my period was late the first day I took a test and it came out negative so I thought it would probably start the next day. It hasn't started still so I took another one this morning and it was negative again. My breath have been pretty sore and I've had some occasional nausea. Am I testing too early or am I just too much in my head?