I doubt you can keep the curl in naturally straight/fine hair.

May I suggest that you find a hairdresser who knows how to cut YOUR kind of hair. Recently I found one who, once she wets my hair, looks it over and see the natural wave (or no wave).then cuts it according to what SHE says is best.

If a hairdresser asks you want YOU "what do you want to do w/your hair", run the other way. They should tell YOU what is best and they are (should be) the artist here.

Note: I've not gotten my hair cut since August and it STILL looks great even as it grows out. That is a sign of an excellent cut!

Note 2 about conditioners: They do the same thing as fabric softeners: coat the hair/fibers with wax which stops friction that causes static. Stay away from conditioners if you want fluffy hair!

Oh, and mousse and thickening gel only dry your hair out. Use your shea butter (the day BEFORE you shampoo) to moisturize it. Then shampoo as needed.