I MISSED MY PERIOD...IS THAT OK??? COULD I BE PREGNANT?????

Ok so im 14 years old and i got my period in 6th grade and im in 9th now. ive never missed my period before and its usually regular and heavy. except for last month it came late now ive missed it. i got that yellow spotting the week i was supposed to get it, and now ive been cranky. is this norma???...COULD I BE PREGNANT?????? everytime ive had ive been protective and i kno that there cant be any sperm in me. HELP!!!!!!!!! PLEASE!!!!!!!!!!!!!!!!!!!