4 days late....

Qu

at 4 days late and possible 18dpo would i have to use fmu or would anytime of day work for testing because every test ive used has been super faint or negative sp please give advice. No there was no stress this month of ttcing we had sex 3 times during my fertile period but im late and its not getting darker it isnt ectopic and i havent had no bleeding just cramps like im gonna start my period but theb i dont. So please give advice