affects of coming off birth control

I am now off birth control for 2 months now. Got my first period right on time exactly 28 days later.  Was supposed to get my period today. Hasn't come yet- but the past few days I've been experiencing some discomfort in my lower left side. It's not severe and it's not continuous. It's really only when I'm stretching or sitting in a certain position and move. I don't have any other symptoms  and feel pretty good. I know your body goes through a lot when coming off the pills so I'm confused as to what this could be. Also a little nervous. Has this happened to anyone? Or does anyone have any input on this?  Thanks so much !!!