R.B.
I know that a "luteal phase defect" means that the fertilized egg doesn't have enough time to implant itself to your uterine lining. A "luteal phase" is the days from ovulation until day 1 of your next cycle. Luteal phases are usually around 12 to 16 days, and anything fewer than 10 days is too short for the fertilized egg to implant, because obviously the uterine lining is shed during your period.
Good luck with conceiving! A great book to read is "Taking Charge of Your Fertility" by Toni Weschler. It's also helpful to chart your Basal Body Temperature (which the book explains.)