Jass, yup, I used clearblue but it showed no line.. total I tried 3 clearblue, 3 guardian and 2 fortel kit. Out of all these, the guardian and fortel's kit all showed faint line except Clearblue. I started testing from 13dpt... the 4th clearblue i tried on that finally showed a faint line was on my 16dpt, one day before my actual day BT...
dont be disheartened dear, maybe the implantation bleeding occur later... like summer said, no AF still got chance... rooting for u... 'hugz'