I know what you mean about having delicate hair and not wanting to use the high heat. My suggestion is usually to do the high heat the first time, and when you reapply use a lower heat setting since you have done the treatment previously. I have pretty fine hair, but I use high heat on the resistant areas around my face and at the nape of my neck.
If I were you, if you can- wait a few days. Often times my hair looks pretty curly right after I apply the treatment, and it starts to flatten out after a few days. Even when it's wet it looks like its going to be curly, but the waves fall right out as soon as its dry. Its strange! But if it's still not your desired look, definitely try it again maybe with the higher heat setting.