As it is, what comes to late periods, I have my own theory...
Women keep getting these: have pregnancy symptoms, might get the slightest positive, period is late, then just BFNs, finally AF comes.
The official reason is "periods tend to be of unpredictable length" as well as "women TTC just want it so bad, so they imagine things".
I call BS!
I've never had pregnancy symptoms or late periods when single, off sex, or on contraception. I've had symptoms and late periods even when I wanted to AVOID pregnancy, so it sure ain't because of wishful thinking.
I think there are two alternative reasons.
A) Fertilization happened. New research shows that the blastocyst/body start emitting hormones (estrogen, progesterone) immediately. The saying "you can't feel it until your period" is outdated. After implantation, hCG is released, and might cause a super light positive. If the blastocyst isn't valid, it wouldn't grow, resulting in decreased hormones and a slightly late period.
B) The egg is not fertilized, but it doesn't die. It swims down and releases hormones (not hCG) anyway. There are research articles on this. Eventually, your body gets the gist and starts a period.
It's very hard to know what really happens at fertilization, as the parts involved are so small. We know that
20% of pregnancies end in the first trimester, mostly in the early weeks. According to new studies, up to
50% end before the first day of the period. Who's to say, if
80% end right after implantation?
Anyway, after extensive paper-reading on animal studies, I also tested on myself. My baseline hCG is 0.01, which I get when off BD. The official female hCG baseline is 0 - 5.
When I've had pregnancy symptoms, my hCG is 0.5 - 1. Even though it's below being pregnant, it's also above my normal status. This means, something happened.
(Yes, we have insanely cheap 24/7 blood tests here, results while waiting...)
Instead of saying "I'm just imagining things" or "my body is so out of whack", we should take ourselves seriously, rest a bit more, eat something nutritious, even take the occasional TTC pause.
... end of rant...
*power hugs*