6d late. 8/17 last af. 28d cycle. mild cramps&headache, sometimes nauseous, sleepyness n a bit of white discharge. 9/18 bfn. possible preg or not?

Negative test: You said your pregnancy test is negative so this means you are not pregnant. If you do not believe the result then repeat it in a few days. Schedule a visit with a primary care doctor to discus your headaches, nausea and sleepiness. Your Obgyn can address your cramps, discharge and irregular periods.

Menstrual cycle: I am not sure if I understand all of your abbreviations here. If you were sexually active then pregnancy is a possibility. You can take a home pregnancy test any time after the missed period. If negative and your period remains delayed - can repeat home pregnancy test in a week with a first morning void. Take care.