I am 17 years old. I have had sex without protection with my boyfriend last month. My periods were due on 5 July and now its 19th of July, still no periods. I hav'nt shown any other symptoms of pregnancy (no darkening of areolar region, no nausea or vommiting, no morning sickness or craving for specific food items,excessive urination.) can I be pregnant?

Absolutely. If you have sex, especially unprotected, you can get pregnant. Most of those symptoms don't happen for awhile, sometimes not at all so I wouldn't put much weight on that. You need to take a pregnancy test.