What Causes Delayed Periods And Back Pain?

hi, my period is 9 days late.i have been having a dull sometimes sharp pain in my lower right back that sometimes reaches around to the front of my lower abdomen. and occassionaly i have the same pain on the left side. i also have had a couple of dizzy spells and slight headaches aswell as preassure in my lower abdomen.i have had tract infections before and have passed one kidney stone, but niether has delayed my period for such a long time. so, im wondering if i could be pregnant.i am very sexually active with my husband and we do not use protection of any kind.