Is my hair damaged or is it just puberty?

Back in 6th grade, i had really smooth and long healthy hair. Then, I started to straighten it once in a while without using heat spray, now its been ever day since then and im in highschool now. I sometimes use heat spray but not all the time. Now my hair is naturally VERY frizzy and fluffy, with a little wave to it. Its very unmanageable and whenever I straighten it, it becomes limp and lifeless. Is it damaged?