Are you looking for a method of birth control that is chemical and device free? Charting your fertility is a great solution. This is not the rhythm method, it does not involve temperature taking, day counting or internal checking.
Fertility is determined each cycle by the sensation felt throughout the day at the vulva (lowest opening of the vagina) and mucus discharged which you can see when you wipe with toilet paper. A quick recording of what you felt/saw throughout the day is added to a chart and soon you will begin to see your natural patterns of fertility. Once you can correctly identify your pattern of fertility through the help of your teacher you can begin to use that information to have sex on the days that you are infertile without fear of becoming pregnant.
Women are only fertile during one time in a cycle; during this time sperm can live inside of our bodies for up to five days. When we are infertile, sperm can only survive inside of us for three hours. The time we are fertile is when we ovulate, there are a few days leading up to ovulation and a few days after that you should avoid having sex to keep yourself from becoming pregnant. Once you have correctly identified your peak time in the month (ovulation) you can have sex any time of the day without fear of pregnancy until your next bleed when you start looking for signs of fertility again.
The few days that we are fertile can be different every cycle; the only reliable way of knowing when those days are is through the correct observations of your fertility that you and your teacher will discover through charting. The rhythm method (assuming that you ovulate on the 14th day of your cycle) is incorrect and puts you at risk for pregnancy because every cycle is different, even if you bleed every 28 days.
It is possible to be fertile during the last few days you are bleeding and it is only through understanding your signs of fertility that you could prevent pregnancy should early ovulation occur and you have unprotected sex on the last few days of your bleed.
Our bodies are actually remarkably simple and give us multiple clues as to when we are fertile so we can make educated decisions every month about whether or not we want to get pregnant. There is no need to be taking hormones, chemicals or inserting IUDs once we know how our bodies operate.