I had unprotected sex with my husband 7 days and he ejaculated inside me. I got an early blood flow which lasted only 2 days. I feel fatigued and lost my appetite and have lower back pains . Pregnancy test reads negative but is it too early to tell if I am pregnant?

It is too early to test if it has just been 7 days. In fact you will not have any pregnancy signs what so ever, ( except maybe spotting) so if you are tired it is not from pregnancy.

You will have to wait to at least 10 days and 14 is better past when you miss your next scheduled period.