Average is 14 days, but normal is anywhere between 10-16, so you are very normal.
http://en.wikipedia.org/wiki/Luteal_phase
Implantation usually occurs between 6-12 days, so a short LP (considered under 9) is a problem because the egg doesn't have a chance to implant. You are fine at 11-12 days. My current LP is 12 days, I'm not worried.