Does anyone know what could have happened to my hair?

My entire life I have had very very curly hair, literally small ringlets, baby fine too, not kinky at all. I used to straighten it every now and then but about six months ago I started keeping it straight, 24/7 for three months straight. One day I decided to stop, and noticed after washing my hair that it was nowhere near the texture it had once been,and I have not straightened it at all for three months now it seems to be straight/wavy permanently. I have never ever had even one strand of hair naturally straight in my entire life, so I'm confused... I understand I obviously did something permanently but I have no idea if it will grow out or... also I did use products while I kept it straight but just straightening leave in and heat protecting spray. Any thoughts?