Suggest Remedy For Missed Periods

The last time I have been on my period was in May. But I don't remember the day it ended or started. Its now August 13 and it still has not been on. Im sixteen years old and my mom said I am changing. But i had sex a week ago on the 4th of August. Im worried that i could now pregnant, but I dont have any symptoms at all. Is there a big chance that I am pregnant if my period hasn't been on in 2 months?