Some things that are getting better:

*Reading, especially accidentals. Three sharps is relatively easy, for four you just add D#. Going in the opposite direction around the circle of fifths, you just B flat, E flat, A, flat, etc... A flat is the enharmonic of G#, so that's the third accidental you add whether in sharps or flats. So about eight key signatures are manageable, leaving four that we'll just ignore for now. I'm reading through a jazz fake book and haven't found more than four sharps or three flats.

*I realized that sqeaks and squawks are the fault of the fingers, not the mouth as I had thought.

*You can't correct a problem in tone quality or intonation unless you first hear it. Ah ha! For some reason C# in the middle register has a hissy quality on my instrument. B flat is kind of strained and wimpy. So making adjustments per individual notes and general ranges, compensations...

*There's a break between B flat, which uses almost no fingers and has that strange quality, to B just above it, with all the fingers and has more resonant. So it's helpful to play pieces which have you moving constantly between those two registers, instead of avoiding having to do that.

*Articulation is getting better. I've been able to play a few phrases that actually sound like musical phrases, giving them shape, rather than just playing everything legato with no tonguing at all.

*Endurance is improving. I can play for longer.