I can see them now, Jaimee. Assuming mucus observations were done properly, both are technically method failure by CM-only NFP methods. Baby 1 was the most common method failure in the sympto-thermal method (and the reason why there are multiple phase I rules: some women's bodies just don't give them enough warning before O'ing.), and Baby 2 was from user error according to the sympto-thermal method.
For #2, I would put O on or around Day 20 (Day 21 is first day of temp rise), but it was definitely BD on Day 19 that got you pregnant. Once you have CM in a cycle, you cannot assume that you are infertile (except before your first PPAF and during some stages of perimenopause, though I admit I don't know enough about that) until you have had an adequate temperature rise. Once you have any CM, you are in the fertile phase, and it is risky business to declare yourself not to be potentially fertile after that until you have clear signs of ovulation.
#1 is harder. How many cycles did you have postpartum that you charted? Your husband's sperm may or may not have actually been 5 days old. CD 13 is only an estimate. You could have O'ed as early as CS 10. Your average O date means very little if you are prone to irregular cycles. What was your earliest first day of temperature rise? What was your shortest cycle length? At the end of the April CTA thread and copied near the top of the May thread, you may have seen some other phase I rules that I gave for people who need a little more accuracy than the Last Dry Day Rule (the most common STM failure). I would encourage anyone who has fewer than 3-6 months experience charting or has a history of mucus patches under 6 days to rely on a more strict rule than the Last Dry Day Rule.
When referring to previous history, don't look back more than 2 years. What your cycles were like when you were a teenager doesn't mean much in your 30's. Also note that after you have a baby, everything changes. If you breastfeed ecologically, you may very well have not had any cycles in the last 2 years, and even if you don't you are much safer assuming that you don't have any history, and if you can't trust the Last Dry Day Rule, you shouldn't go past CD 6 until you have 6 cycles of history postpartum or until you are having fertile (adequate LP) cycles, whichever comes later, if there is a strong need to postpone pregnancy.
That pg sadly ended in a M/C but we went on to get pg with the little one that is currently kicking the top of my belly because I've been sitting for too long!
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