AF due 5th but still getting BFN..........

Emma • Pregnant with baby boy #2 due August 2017
I know it's early but only only by 3 days. I'm still testing BFN I know I'm not out until AF shows her ugly face but I can't help feeling disheartened. I know some don't get a bfp until after AF is due but just thought if it was my month then I would have got a bfp by now. 😔 I've had so much cramping past few days, dizzy when I stand up, back ache at night etc but don't know if I'm clutching at straws. AF is due Wednesday 5th. Am I just testing too early as when I did tests last time with my 1st I tested positive at 8dpo. Would appreciate your comments xx