(I'm not sure if this is on the right board so let me know!)

We have been using Natural Family Planning (combined with the withdrawal method) to prevent pregnancy for the past six months. I wanted to go off the birth control pill because it made me feel terrible, and I thought it would be good to get to know my natural cycle before TTC in a couple years. So far, my periods are terrible, but the rest of the month is much better! And I'm not pregnant yet so it's been a success.

I track my cycles using an app on my phone, and we use the Standard Days method to determine whether it's a "safe" day or not, so I'm not temping or charting or anything. For the first three months, my cycle was exactly 28 days long. Then the fourth month, it was 29 days. The fifth month, it was 31 days. Then this month, it was 32 days.

At first, I was so excited that I was going to have a cycle "like clockwork." Now I am nervous that they are getting progressively longer. Is this normal? I worry that it could mean something for my fertility long-term, and short-term I worry that without a super regular cycle, our current form of NFP won't work for us.