Welcome and condolences, Pregnova. 3 miscarriages would be almost too much to bear. Do you have any ideas on what could be causing these miscarriages? One of the great things about charting is that it can be useful for assessing the health of your cycle, which may help you to get information on what is going on and could help get you to the root of the problem. For at-home things that you can do to increase your fertility, I would see if you can get your hands on a copy of Marilyn Shannon's "Fertility Cycles and Nutrition" (Amazon link in the "Resources" wiki listed in the first post). If there is something for which you would need to seek medical care, you may be able to find a physician trained in NaPro (Natural Procreative) Technology (links in Resources wiki) that could read and diagnose issues based on your charts (NaPro physicians are trained to look at Creighton charts, though many are adept at looking at Sympto-thermal charts as well, especially if you keep copious notes on your paper chart about CM characteristics (color, consistency, texture, amount, etc.), and they have developed a method of medical care that can successfully treat most problems of infertility/early miscarriage with a better success rate than IVF. Now, I'm not one to push medical care when most things can be solved through simple nutrition. I just want to let you know what your options are as you begin charting so that you can choose that route later if you see a need.
Butterflymomma is right that you will count the first day of red blood, the day of your miscarriage, as CD 1. (Butterflymomma, I knew it wouldn't be too long before you were the one giving people information!) You will need a basal body thermometer (often just sold as "basal thermometer") to temp. The Walgreens one tends to get bad reviews. A lot of people use the BD (Basal Digital) one, but there are many out there that work well. Note that you have to take your temp at the same time every morning to get good results. Some women can fudge this a bit or adjust their temps for waking times, but when you're just starting out, I highly recommend setting an alarm for the same time every morning.
Librarygirl, I'm sorry to hear that you had to go through that. How awful! A 10 day LP is short, but it is theoretically long enough to sustain a pregnancy. Really, if you can get implantation to occur, you're probably fine for sustaining a pregnancy, and implantation almost always happens by 10 DPO, so on that count, I wouldn't say that it is any more likely that this was an early miscarriage. Also, a pregnancy that does not last long enough to delay AF is not usually any worse than a regular AF. The reason miscarriages that occur a little bit later can be so much worse is that the HCG tells the body to build up the lining more instead of shedding it. If this didn't get a chance to happen, there wouldn't be more lining to shed. Of course, there's not a way to rule out the possibility that a newly conceived life was washed away in any period where there was a possibility of getting pregnant, but from the information you give, I wouldn't think that it is much if any more likely than in a normal cycle.
It does sound like something went terribly wrong, though. It is not normal to have your LP jump down by 3 or 4 days, include PMS symptoms that are not normally present, and have such an awful period. My guess would be that they are all related to the same cause. It could have been a fluke in your hormones, or it could be a sign that your body needs some extra nutritional support. I would also recommend Marilyn Shannon's "Fertility Cycles and Nutrition" to you.