My gal friend and me had sex twice at 20 & 22 Nov 2008. we used condom during intercourse but not sure 100% that it worked perfectly. She had her first period after this delay by 2 days, then second on time but both were not as long as she had earlier...now this is her 3rd and it's delay and already delay by 2days and still not had...she is very tense off course, because we are not looking for baby.

please suggest is this a sign of pregnancy or some other reason,
Can she use home pregnancy kit to ensure this at this stage.

plz suggest :-(