Could Spotting Be The Symptom Of Pregnancy?

I am 19 years old. I had unprotected sex with my boyfriend but I am on the pill. I have been taking Loestrine 24 Fe for 9 months now. I have been having my period for the past 5 years and I never have irregular periods or spotting. Even after starting birth control I never experienced spotting until now. Is it possible that I could be pregnant?