Re: how to calculate my unsafe days after period
MusicElle is correct. FAM can be an effective means of birth control, but only if you do it correctly and consistently, not to mention, you need to chart your cycles (basal body temps) for a couple cycles to get the hang of it beforehand. A good book on the subject is "Taking Charge of Your Fertility". FAM is not the same as the calendar method, and for me, I never took chances; we used condoms from cycle day 3 onwards until I was 100% sure I had ovulated that month (confirmed by an obvious 3 day rise in basal body temperature and the dry-up of my cervical mucus). FAM was very effective for me; I used it 9 or 10 cycles to avoid pregnancy. Then, when we started trying to conceive, I got pregnant on the 2nd cycle trying since I knew from charting that I tended to ovulate from cycle day 11 to cycle day 18.
BUT...I have a feeling this is more work than you are willing to undertake. You have to be diligent about it, and my husband and I were not opposed to an "oops" if it happened.
As far as the calendar method of birth control, it does not work. Period.
If you want effective birth control, use condoms or get on the pill.