I learned my method from the book Taking Charge of Your Fertility by Toni Weschler (I highly recommend it, but it is a fertility awareness book, not a NFP book so she is not against barrier methods during fertile times, so just ignore this), because I couldn’t understand the NFP book, so I am not sure what the difference is between the Creighton and Billings methods, but basically I mainly check my mucus, so I think I am doing what you are. I have done this for about 5 years, including while I breastfed my first baby.
I did intend to use all three signs: mucus, temp, and cervix position. But I have horrible insomnia and it made getting a reliable temp difficult. Then I started taking sleeping pills, and it just got harder. I wasn’t seeing any kind of pattern that I was suppose to, so I gave up. Although I like the idea of cross checking, it just didn’t work out for me. I do still try to check my cervix position (well, when I am not pregnant), but this is difficult for me, so I mainly rely on mucus types.
It depends on your source. Although, it makes sense, because you can cross check, but ultimately, I think checking your mucus is so effective, checking your temp is just extra security. Unless you have trouble defining the types of mucus or your body doesn’t produce good mucus, then I could see checking your temp (in addition to mucus) being more effective.
It is very easy to do, for me. Basically it looks like eggwhites when you are fertile. Some women don’t produce good mucus, and they may have a harder time, but if you check every day, you do start to learn your body and are able to discriminate better over time.
No. Several times we had sex at times where it was possible to get pregnant, and twice we became pregnant. I do not consider that a mistake, because we knew there was a chance that I could get pregnant.
The biggest factor in not having “good” mucus are nutrient deficiencies (especially zinc, calcium, magnesium, vitamin A and Iron). The most important thing is to make sure you have enough fruits and veggies every day. There have been many cases of women having trouble discriminating the types of mucus and after they changed their diet they had a much easier time.
Other meds than can affect your mucus (most cause the mucus to dry up): antihistamines, guaifenesin (which is the active ingredient in Robitussin), Bisolvon (this one actually creates more mucus), some antidepressants, some herbal medicines (such as golden seal and horseradish), high doses of the acidic form of vitamin C ascorbic acid, prescription antibiotics, and, oddly enough, Clomid, a fertility drug, also affects mucus.
Fortunately, most of these meds (with the possible exception of the antidepressants) are taken only temporary so you can abstain during that time to play it safe. Although every woman is different and one dosage might affect one woman and not the other, so you may not notice any change.
Also, remember that lubricant and seminal fluid can sometimes be mistaken for mucus, but after awhile you usually can tell them apart, not to mention they only stick around for about 24 hours after intercourse, but it is good to keep in mind, especially in the beginning of learning to chart.