[DS having an early sneaky snooze so I have spare time to internet rather than do housework]
Yes, so Dr Internet says that a normal Luteal Phase is 12-14 days long. But... honestly... who on this thread would count themselves as "normal" though? 
I can't speak for anyone else, but after having DS I can honestly say that EVERYTHING is different. Cycle timings, feelings, AF type and length, absolutely everything. First time round I faithfully charted and this involved visual inspections (and this is different too these days).
Then you have the ladies who have also had MCs. Surely that screws around with your body a fair bit.
So, is it any wonder a lot of us are working on educated guesses?
We shouldn't be hard on ourselves for getting our hopes up or for feeling disappointment.
I've decided that if I'm not PG then I'm about to fall down sick. Had awful headache and hot flushing last night and woke this morning to discover TWO cold sores starting (I admit I look a right mess).