I am almost convinced my hair is fine, but it seems like 1C hair, please help!

Do you think my hair is fine? More context below.

I have medium thick hair that are kinda heavy , especially when long and in a ponytail. They have always been hard to style because some strands get slightly wavy and some remain completely straight (first photo), making me look super messy and unkept. It gets oily at the scalp quickly, but the ends are dry. I dye my hair for about 10 years now and I feel like my hair has become super soft and fine over the years. When I was younger I believed my hair is actually kinda coarse, but now I am reaching my 30s and it just seems super fine (or I just didn’t know anything about hair types, but I did hear that hair type can change).

It never holds any curls or volume unless I do overnight heartless waves, but it will only last a few hour. Curl iron does absolutely nothing, I also don’t bother with straightening them because it will have those occasional waves again in less than two hours. I am at loss, I don’t know what to do to not look like I just woke up from a bench in a park. My hair is somewhat healthy, but styling is a nightmare.

I use lightweight products – shampoo for colored and fine hair (Wella) and clarifying shampoo (Elseve) once a week, followed with a conditioner (volumizing) only on mids and ends, after that I spray my hair wirh Gliss Kur leave in conditioner focusing on the ends and seal it with a drop of hair oil only to the ends. For styling I kinda gave up so I am only using a bit of volumizing mouse after my hair air dry until damp and put it in a bun overnight. In the morning it has a slight volume but still will look messy as hell in couple of hours. Sometimes I just let it air dry as it is and hope for the best.