Missed AF, but still have symptoms?

Tonya
I'm on CD33. AF was due Sunday (12/6), I took a hpt the day before and got aBFN. Sunday night, Monday and Tuesday I've had the cramps from hell! Still no period though. Should I test again? I just don't want to get my hopes up. I'm thinking I'll wait until Friday (12/11) and if still no AF, I'll buy a non-digital test. All I have at home are digital...but I just found out that I have to produce more hormone for the digital to detect it. 
I also used letrozole for this cycle so idk if that has anything to do with it. Any thoughts or anyone been through something similar with AF symptoms, but no AF?