I don't think you have the right mindset or focus for the tv sync business. You want to be an artist, doing things from your heart. I wonder how you would feel if you were given feedback from a library requesting changes... would you say "no, that's not how I feel it?"
Taxi offers hundreds, if not thousands of new music listings every year. To be "dissapointed about the amount of opportunities they have to offer" is an uninformed opinion. You are choosing to limit yourself for your art, that's not Taxi's problem or any music library's problem. I suggest you continue writing the music you love, focus on the best possible quality from a production perspective, build up a catalog of what you enjoy, and then self publish via Spotify, etc. This way you maintain complete control over your musical direction and you serve your personal goals. The music sync business is a business, composers in this business are delivering a product to a market, and success depends on supply and demand.
Best of luck.