Ok I had unprotected sex on my fertile week in February my period is now 17 days late which is very unusual I'm always on time every month. I'm not trying for a baby as I'm only 19 and still in university and I have another 3 years to go.i took a test when I was 11 days late it said negative so I didn't worry anymore. But a friend said to me today I could still be pregnant because I told her I'm having really bad back pains and lots of discharge she said that's symtoms of pregnancy is this true ??