Ovenbun, my lp was also short, about 9 days. Now I have no way of knowing if it had anything to do with my two losses, but when I finally convinced my doc to do a 7day post ov progesterone test, it was really low, barely near the level that would even convince docs I was ovulating, which clearly I was cos it's the same cycle as got me preggo now! Anyway, I'm on progesterone pessaries and (fingers still crossed) I've never got this far before. The important thing is to get tested 7dpo, not just day21. Stick to your guns! Hope that helps.
Fairy x