What a great post Ben! Thanks for sharing your struggles and accomplishments with us. It’s really nice to hear that you have reached lesson 14 and are really following the course as it is designed. Don’t worry about the lessons in front of you, once you have these skills under your control, there is a lifetime of harmonica playing in front of you! and I can truly say that by mastering the clean up, you are well and truly on your way to being able to play anything your heart desires.
As to your clean sound, ha, that is the best as you can always make a clean sound gritty but it’s harder to make a gritty sound clean! So, are you referring to a gritty acoustic sound? or perhaps do you mean you’d like to experiment with an amplified distorted sound?