The diet was a good suggestion because at 16, with your last straightening session 2 years ago, I wouldn't think you had damaged hair. Do you color or are you a swimmer?

Along with the protein suggestions, try a commercial deep conditioner rather than the oils - I like SS Deeply Decadent.
High Density, High Porosity, Medium Texture, 3B with some kink

Lo-Poo: No Preference
Co-wash: CJ Smoothing Conditioner
RO: CJ Strengthening Conditioner - HG
LI: CK Satin Roots
Styler: CK Coil Jam
Other Likes: Castor Oil; CK Twist Whip, MD CSC
Dislikes: Wheat Protein; Aloe LIs or Stylers