My AF was due 2, nearly 3 days ago..

I've not had painful boobs, or other symptoms i usually have with AF.

Ive been feeling quite sick for the past few days, getting little twinges in my stomach but im putting that down to the fact i keep getting constipated. this is unusual for me as i normally dont have trouble. (Sorry if its TMI)

I thought i would take a test and its come up as a BFN.

My AF is usually on time each month aswell.