When do I test again?

Hi girls, I am now 6 days late for AF. Have cramps, feel a bit nauseous, a bit insomnia, and just generally don't feel well. My husband and I have been TTC for 3 months. I have tested 4 times, all saying negative. I put in tampons thinking my AF is coming, but nothing is happening besides white, yellowish discharge. This waiting is killing me!! Either let me have AF or let me know I'm pregnant!! Ugh. When should I test again if AF still doesn't come?