I am 18 years old and have usually been pretty regular but the last few months my period has been moving around or shifted from being regular-to heavy to very light and back again. I know that this is probably from stress. I have never had unprotected sex with my boyfriend and we are always very careful but I am now seven weeks late. I have taken three tests and all of which have come back negative. I havn't had any symptoms but should I go to the doctor's anyways?