i have shoulder length hair that was cut very very thin during my hospital stay so that it is easier for my

I wouldn’t use it. 1. you should give your hair time to rest and do it’s thing. Hot tools would only damage it and make it break. 2. it will cut out volume and with thin hair it wouldn’t be as flattering for you.

If you insist on straight hair do a hair wrap. but for more volume you can use rollers WITHOUT heat to do the trick. for more culy hair use smaller rollers, for more smooth hair use larger rollers. for more volume set them higher up on the crown regardless of what size roller you choose. Hope you’re feeling better, by the way.