From my point of view, and as a mostly all text-journaler (wall-to-wall scrawl except for the rare cut & paste in's) I would like to first say that YOU ARE NOT DOING IT WRONG.
I think the focus is more about discovering who you are. In my opinion, that takes a combination of experiences and reflective thought. Writing - especially about daily living and even more, "about what's happened and how I'm feeling" - is part of that process. It is the discovery, page by page.
Let's say I look back at my writing from when I was a teenager - I didn't know much about myself at all but my gosh, reading it, that's who I was and I did know something as I wrote about myself and how I felt. These days, I'm more often to write some stuff that just feels blah or rambling or whatever but when I dig in and write about what's going on and how I am actually feeling or what I think about something, I think it's also showing me who I am, now. I've changed a lot since my teens and it shows through my life experiences and how I write (or don't write) in my opinion.
But it's just one part of it. Keeping a diary or journal is one part of it. And when I open my journal it doesn't have a choir of heavenly angels sing but I do feel like it's a place I can write for myself. Whether I'm writing about my bowel movements, sex, wish lists that never come true, confessions of overeating or the same damn thing over and over again --- it's whatever I want to write, or, whatever I'm writing just to let it onto the paper instead of blurting it at someone else who doesn't need to hear the cyclic noise.
If you want to make your journal more magical or "heavenly" you could approach the page differently. The time you set to write. The words you put down. You could see it all as this incredible and unique document unfolding entry by entry of your life.
It's the supposedly mundane, the real grit of life, the feelings, the thoughts, the glimpse of who you are - in whatever form, text or art - that makes for a decent journal.
Your life experiences and what you learn or take from them into who you are is what makes you become your self. It can change or it may not. Personally, as a text-journaler, I'm ready for a change in my writing - I'd like to see me put a bit more feelings and details of my life into my journals like I did when I was younger. It was when I felt the least self-conscious about writing.
You're not doing it wrong. Do you know who you are? Are you evolving, staying the same, in flux, searching? You're not doing it wrong.
I can't believe I wrote all that on my phone!