I absolutely hate Cantu Shea Butter. It made my hair feel dry & like it was coated with plastic. I normally use conditioner as a leave-in. My fave right now is V05 because it isn't super heavy, and I seal it with a little grapeseed oil.
Have you tried any protein treatments to treat your heat damage? I don't know how long you have had it but sometimes protein will help to restore some of your curl. Also, you don't have to cut all the damage off at once if you were considering cutting your hair. You can gradually trim. One more thing, for the hair that doesn't curl much, you can try scrunching while your hair is wet to give it some curl.