Could I skip a period or could I be pregnant??

Okay Ladies,

I have never missed a period In my whole 29 years of living. I have been late before (typically no longer than a week which rarely happened). My periods were usually pretty predictable. So my period this month is late by 13 days and I have no signs of really being pregnant that I can tell. I have taken two pregnancy test and they both came back negative. The first test was the day of my predicted period so it’s not like they are early; and the second one was 7 days late. My husband and I did have sex but it was not around my high ovulation times so it doesn’t add up to me? What are your thoughts? I am still breastfeeding my almost 1 year old so idk if that has anything to do with affecting it... just curious what other mommas have experienced.