Spotted then nothing

My AF was to start on Friday. I started to spot Friday morning but by today there was nothing. We have been TTC since August of 2013. Never have used any preventatives (birth control, condoms, etc) This hasn't happened before for me. I've always been pretty regular with the same AF process every month. Usually light the first day, medium the next, heavy, heavy, then fades out, lasting always five days. Any ideas, advice, or input?? I just don't want to get to hopeful! Thanks!