Is This Niche Small Enough?

I have listened to the “Formula for Value Creation.” I did the niche worksheet, and I am listening to “Expert Secrets” by Brunson.
I have been trying to write and finish an online course for over a year.
I am a singing teacher.
Question: Is it a specific enough niche to write a course for singers who experience tension, strain, vocal fatigue when singing who want to sing with ease, freedom, and expressiveness?
Two other components that came up when I was interviewing my ideal client is that they want confidence and vocal consistency, as well as finding their own voice.
I am really struggling refining my niche.