That happened to me the cycle before this one; AF 10 days late, I was feeling sicky, sore breasts, off food, slight weight gain... just as I was about to do a test (the one cycle I didn't want to fall too, but the excitement was growing), AF arrived. Heavy, bright red, clotty... then this cycle was a short cycle (well, for me at least, which means under 5 weeks) but because of the screwed up 8-week cycle I'd had before, I didn't find out until I was 2m gone! This time I wrote off any symptom I had as "well, I ate late last night, probably why I'm feeling iffy", "Hey, I've put an inch on my chest... does this mean I finally get the good points of puberty?" "I'm so tired - probably because I've just done a de-tox and am off caffine." "Wow, that must have been a bad bottle of wine, I can't even finish one glass!". I just didn't want to get my hopes up at all.

If it was 2 cycles ago and there's still no positive - because now you'd be in the second trimester and your hCG levels would be falling - then it sounds like you've had a "phantom pregnancy", where wanting to be pregnant gives you some symptoms.