That's looking darned good for a first attempt at spraying mottle, and even better after diffusing the starboard side.
That initial problem you had with the 'brush not spraying could have been an air lock - test by blocking the nozzle with your finger and briefly operating the trigger, keeping your face away from the paint cup. The paint should bubble-up in the cup. The test spray as normal, and it should spray.
If not, empty the cup, blow through using just the paint remaining in the 'brush, cleaning the barrel if required, and try again.