Criteria for narrowing down my niche

Hi there!

I am a weight loss coach and my business is growing. I hit a 150k this year and am completely stoked about that. I would love to double my income next year and believe that I can. Coming up with the how I feel that narrowing down my niche will be a great step forward. My question is what are the best criteria for narrowing down?
My current marketing message is as follows: Have diets stopped working for you? I will teach you how to lose weight and keep it off without willpower.
I target woman between 40 and 50.
This is too wide of an audience.
My 1 on 1 coaching costs 2200 euro for 12 sessions (supported by my online program)
My group coaching costs 995 euro for 12 sessions (supported by my online program + Facebook group)

I love working with smart women who are curious about the connection between their brain/thoughts/feelings and food and are interested in their personal development.
They want to lose weight. But they also want to get rid of all their mind drama around food. So, they love doing the thought work and homework that I provide.
They are also willing to pay well for my offer. They see the value.
They are my ideal clients.

This is just spoken from my heart and experience, but when I read it, I miss the specific definition from the worksheet.
How do I solve this? What can I ask myself? If this requires coaching, I’m up for it!