Okay brace yourself this is gonna be long.

I got most of this from a book "The Infertility Cure", like I said, it's an Eastern medicine approach. A lady on JM called Norina told me about it. She had 2 or 3 m/c and then had I think about a year where she didn't get pg (whereas before she got pg quickly) and she followed some of the things in this book plus did accupuncture and now she's about to deliver any day. (Accupuncture is something I've been thinking about)
Anyway, it talks about all these different things that can be wrong with your cycle or out of balance. There is a quiz in the book. The one that really struck me, they call "kidney yang deficiency". Here's the basis of it: there are two energies, yin and yang. Yin is cool, dark, feminine, and this is your follicular phase. Yang is hot, masculine energy and that's your luteal phase (makes sense because it is ruled by progesterone, which is what makes your temps raise during the luteal phase). Yin and yang must be in balance with each other, if they are not you have problems.
Symptoms of kidney yang deficiency: Lower back pain premenstrually, cold feet (especially at night), typically colder than those around you, low back is sore or weak, libido is low, you are often fearful, waking up at night or early in the morning because you have to urinate, urinate frequently with the urine often dilute and/or profuse, early morning loose, urgent stools, profuse vaginal discharge, menstrual blood tends to be dull in color, feeling cold cramps during your period that respond to a heating pad, your tongue is moist, pale and swollen.
If more than a third of these apply to you, you may suffer this problem.
It also talks about something called cold uterus, which is when your uterus is not responding to the heating effects of progesterone. You may have this if your abdomen feels cooler to the touch than the rest of your body.
Diet: Do not consume ice cold drinks, as that lowers the heat in a body that is already heat deficient. Eat organic or homone free meats whenever possible, cut out caffeine, nicotine and alcohol, Add to diet: black beans and legumes, kelp, parsley, sprirulina, chlorella or blue-green algae, wheat germ, wheatgrass, string beans, mulberry, millet, non-hormonally treated organ meats, oysters, clams, lobster, crayfish, tofu, raspberries, walnuts, wild rise, pork, venison, chestnuts, black sesame seeds, Lycium fruit, adzuki beans, yams, gelatin, corn. Eat warm, nourishing foods. Include gingerroot, black beans, lentils. Grains like oats, spelt, sweet brown rice and quinoa. Fruits including citrus peel, dates and cherries. Vegetables including parsnips, mustard greens, winter squash, cabbage, kale, onions, leeks, chives, garlic, scallions. Cook with peppers and warming spices such as anise, ginger, cinnamon, cloves, fennel, basil, rosemar, dill, caraway and cumin. Stay warm. Take warm baths, warm your feet, warm your lower abdomen with a heating pad before ovulation.
I don't go too crazy with it, but if I am able to add a few extra things from the diet then I do. I eat more black beans, green beans, walnuts, because I like them anyway!
And like I said, I don't know what had the effect (the diet, the heating pad, the room temp drinks) or it's a combo but *something* has worked because I do have longer LPs. This may not work for everyone, but I think it did for me because I do believe I fit that particular problem that was described in the book. There are lots of other deficiencys and problems that are described that may fit you (or me, I am just not sure about a few of them).
If you have any further interest, I'd suggest reading this book! I've just been checking it out from the library. It can be a bit confusing, but there is some good information in there.