Just start writing about your street photography bc that’s already specific enough? I think your niche will get more clearity for yourself when you just do it, you’ll slowly start to understand your proces. When you’re thinking too much about your niche you’ll get stuck in your thoughts; paralysis& analysis.
I’do also struggle with a ”niche”, I shoot (street)photography because it helps me to get out of my anti social comfort zone, but I also shoot nature, structures, objects, portraits, surrealism etc.
And I blog about mental health. I know that my area is super wide, but slowly I see that that is what can make me unique; my wide area.