There comes a point between testing way too early and getting close to my period at which I start becoming exceedingly pessimistic. I feel like that line is very thin. One day I'm feeling OK because it's still early, and the next day I've lost hope because I should have seen something by now.
The first time I got pregnant, I didn't test until five days after my expected period. That's what you get when it's a total and complete surprise. The nice thing about it was that there was no guessing. I looked, and I saw two equally dark and clear lines.
If I had self control, I'd wait until after my period is supposed to come to test...then I wouldn't have to draw the thin line between blind optimism and complete and total pessimism.