Missed period

I just went off the pill last month (around thanksgiving) and immediately started to bleed. The first day of my last period on the regular schedule was nov 13th. I have yet to get my period and don't have any sign of it at all. 
I took a pregnancy test today which came back negative but I'm a few days behind already and weeks behind if I were basing it on my normal cycle. 
Anyone have any thoughts on this? Is this normal when first getting off the pill?