Possible cycle change?

So, I am 1 day late. For over a year my period was regular and it came EXACTLY the day it was supposed to, except for last month when I was 1 or 2 days late. I have experienced usual pms like I do every month (tender breasts, irritable moods and a bit of cramping), but no period yesterday, when it was supposed to come. I mention that I know when I’m ovulating because over the years I figured out how to sense it and it coincides with the fertile window on the app. I didn’t have sex near that period of time (2 weeks in total). I did have unprotected sex a few days ago though, but he didn’t come inside and I’m sure that I wasn’t ovulating. I heard about multiple ovulations but it is not the case. Could this be my cycle changing?