Please Help! Need advice

Hi ladies, I need some advice please? I have completely missed my period this month. I am usually on a 28/29 day cycle. I have done 2 hpt both negative. one on the day before AF was due and then again on last week Friday. I feel the occasional nausea and had some lower abdominal cramping (different than period pain) but thats it. Could it be due to hormones being all out of whack? What do you think? Should i test again? Or get bloodwork done? Also, I am not sure if we are missing the mark on our BD approach... so confused!