Shannon, this was a very detailed story and useful for others who look at being “self-employed” as being the new American dream.
As one who has been freelancing for 40 years as a side-hustle (we called it moonlighting) I have seen many writers seduced into this same situation, which is really not new or unique to the gig economy.
When I first began writing I was a self-employed painting contractor by day and writing (freelance articles) by night. That painting contractor sitch was similar to yours in that SOMEONE ELSE was doing the part of getting the clients (Aprartment building owners) and we were doing the work. It seemed a fair split to me. We got 70% of the fee for what we did, and fed 30% to the guy who ran the business and orchestrated jobs. After two years he changed this to 60–40 though. We charged $10 per room and $10 per ceiling, with extra charges if there were baseboards, window sills etc.
When the rate changed, I decided to leave the team and do my own work where I received 100% of what work I did. The primary reason was that it seemed the owner could arbitrarily change the arrangement to 50–50 in a year or two, and I wanted more control of my life.
My Point is that this system work/worker relationships has been used in many situations. Many housing contractors do the same… sub-contracting. You bring your own tools, cover your own costs, insurance, use your own vehicle…
The last part of your post is a key. How do you value your skills and time?
Most freelance writers have a per hour fee that they charge (though they may waive their rate a bit for a steady client.) As you get more work you raise rates on new clients, etc. I charge X dollars an hour and a friend charges 4-X because of his lifetime expertise and reputation. I am in a smaller market also.
Sorry for rambling. You are clearly an excellent writer, as your story is coherent, engaging, and useful. Life is long and one day you will look back and see this as an educational experience. It cost you something, but also gave you much.
Wishing you the best.