HI I have gone through your mail and as said you were having flu infection with typical picture of symptoms like -fever, chills and rigors, nasal congestion
and discharge,coughing etc about one week back.now after one week you developed nausea though no vomiting
is there, this is less likely to be due to flu as you are missing your period of menses one may think of conception.As you have told about contraception
(following safe period method) may sometimes gets fail.you are now advice to go for pregnancy
test to rule out pregnancy.