Little worried

I'm on the pill 4 months postpartum last week I had a day where I spotted which I thought was the start of my monthly but it wasn't and now a week later I'm a day late... I miss one just one pill the very being of January is it possible I'm pregnant part of me thinks I might be but I think I'm just freaking myself out more than anything.. I plan to wait a few days see if my period starts if not then I'll test but what do you ladies think and what has been your experiences