Bleeding a few days after sex

hi i am 16 years old and have noticed that after i have had sex i have had light bleeding after sex. Last year was my first time and the same thing happened, light red bleeding a few days after sex. My partner at the time did not use protection and i went to a planned parenthood place and used a pill

it is now a year later and i had intercourse with my boyfriend who did use protection. the same thing happened. it does not hurt, just light red blood on and off. what could this be? i am freaking out thinking i could be pregnant.