Hi. I have been having unprotected sex for the past 6 months n have gotten a period each month at my right cycle time usally the 7th. Now its dec n i still havnt gotten my period when i got it all the other months. We have sex almos daily also. My back has been hurting the last month too an its been unconfertable. Also the last week its been really hard for me to get to sleep confertable with my back hurting too back cramps. I also got just sore nipples 1 week ago. I usally get sore boobs n nipples before my period but this time no period yet what could tgis all mean and when should i test or am i not preg at all since the othr 5 months i didnt become preg an im 18