Yo and congrats on first lucid!
It sounds like you are too awake for falling asleep. You could try changing the period between waking up and WBTB a bit or changing the wake up time or try doing less active tasks, experiment with it and find a time that works the best for you.
Also are your headphones comfortable enough though? Also i suggest you to work on developing lucidity related skills such as awareness instead of relying on binaural beats entirely for becoming lucid, but they are good for relaxation though.