Because I have been charting, I've been able to determine that when I actually ovulate, my luteal phases are usually 12 days, but last month it was 11. My doctor says this is normal and acceptable.
According to the reading I've done, a "normal" luteal phase is usually between 10 and 14 days. It has to be at least 10 days to sustain a pregnancy. I have read that in several sources, but the only source I can specifically remember the name of is "Taking Charge of Your Fertility" by Toni Wenschler (
www.tcoyf.com). THIS BOOK IS AWESOME and I'd highly recommend it.
Best of luck!