Hello in june i had dry sex with my boyfriend and he eyaculated a lot on his pants i had my undies 2 days later my period came so the next month it didn't come when i had like 9 days of delayed i went to the doctor and she told me not to worry and she made me do a blood pregnancy test i did it next day it was negative, buy my concern is that my period still is not coming sometimes y have like pain in my lower back or in my belly but no menstruation what is it? can i trust that test i took?