Off BC to get back on track....period is about 2 weeks late.

Hi, I am just a little concerned about my period and wanted some insight from others! I had to stop taking my bc after my last period because there was a mix up between my pharmacy and my doctor. My perscription was available to me too many days after the Sunday following my period, so I decided to be off birth control this month-- wait for my period and start the pack the Sunday after I do get it. I was taking y birth control as normal for dec-jan and got my period about the 15th of January and planned on taking my birth control that Sunday but I like I explained above I couldn't. I'm in a long term relationship and we have had sex while I'm not on bc and I'm still waiting for my period to come. I took a test just for precaution and it read negative. Just curious if my body is changing from not being on the pill and how long can this last?