6 days late, but negative pregnancy test

I took a pregnancy test today as I was 6 days late on my period. I just came off HBC January 3, and my first two cycles were perfectly regular at 31 days + 28 days. We use the pull out method and I practice the fertility awareness method so our risks are very low, however I was a bit concerned since I'm so late. It was negative, but I'm still concerned because I haven't missed a period in nearly 8 years. Do you think it's something to worry over? I canceled my GYNO appt because I didn't need a Pap smear this year but should I go just to ask him about this? Infertility is a big fear of mine and in about a year or so my partner and I would like to start trying. Any advice or reassurance would be appreciated 🙏🏼💛😊