General ttc

Hey ladies! My period is always on time & always starts the same day every month. In October we did the deed a few days before ovulation & the day of but my period for November was like 1 1/2 weeks from starting. I had my November period but for December I’m already 4 days late no signs that it’s coming either.. should I test? Should I wait? Is it possible to be pregnant even though I had my period in November!?