so im a 17 year old girl and ive never had sex in my life like NEVER im still a virign but one day i was Masturbating and i remember that in the same place i did it my boyfriend did it as well i dont think the sperm was fresh bc i didnt feel any wetness and that happen an hour ago im now 4 months late for my period and my stomach is kind of growing last period was august 10 did a blood test on sept 13 and was negative keep testing and all negative dont know what to do help !!! my periods were always regular