It takes a lot of reflection and self-awareness to do this kind of evaluation of your own process and the results. It’s awesome that you are though, you’re absolutely right, writing is a practice and you just have to keep working at it. No matter how far along you are, you never outgrow the practice.
I also very much agree with the need for writing…a lot. It’s the only way to grow (and give yourself all those opportunities to reflect and learn). I think what you’re doing is inspiring and I think you’re spot on.
Also, one neat way to generate more original ideas is to simply link old ideas together in new ways. Your journal can be a great way to help with that.
Or, use index cards. Just jot down snippets from things you’re reading, spot on YouTube or hear in a podcast, cite your source and come back to the cards when you have a stack. Jumble them, and see what pops out.
If you’re curious about this kind of process, look up the Zettlekasten method. You can make your own version but it’s pretty inspiring.