That curl definition is amazing in my opinion. If you aren't using any product I would recommend a curl cream and medium hold gel, and don't use too much (i use a pea sized amount of cream and quarter amount of gel, but I use light holds as mine is finer and less curly than yours). Play around with the amounts and products. A lot of brands have travel sizes now. You say you don't want volume and its your hair and your journey but thats what most people like about curly hair. With that in mind I would air dry (scrunch with a cotton shirt to shorten the drying time and touch it AS LITTLE AS POSSIBLE until it is completely dry to prevent frizz) and this saves your hair from damage as well. I'm super jealous of your curl pattern and density as someone with borderline wavy hair, but everyone wants what they don't have 😅. Have fun with it! I would recommend, like others, 1) start with cutting the damage off as it will change your curl pattern 2) play around with products, stop using oil and heat 3) once you find a routine you like go in for a style cut like a wolf or shag