stopped birth control, Back aches, and cramping

I stopped my birth control last month (nov) my perscription ran out. anyways my last period was on nov 1oth, i was about 8 days late with what i think was my period it was very light and lasted about 3/4 days(no clots, or very red) and i was cramping several days before that, and a few days after the bleeding stopped, a week later i have been having back aches, i took a blood test(pregnancy) it was negative on dec 19th....baically im wondering if the back aches,light period and cramping is all normal for stopping thre pill, or can i still be pregnant??