My period is one week late and I am concerned about pregnancy.

I’m tired, have nausea, swollen breasts, and “super senses” (smell and taste). I have also experienced cramping and emotional mood swings (crying jags, but for the most part feel strangely “calm” ;). I have tried two different types of home pregnancy tests (“Answer” and “EPT”) and both are negative.

Is it possible to still be pregnant?