Two days late

Last period was Dec 21,2014 and ended on the 29th.. Was very light. Had sex with my fiancé on the 30th unprotected as we are planning for another baby.. I was supposed to start my period yesterday, I didn't start and still nothing today.. My boobs have been hurting for about a week ina half the back on my shoulders are tight.. I feel tightening in my lower abdomen, nauseous, dizzy and massive headaches.. Could I be pregnant?