A serious student spends much more time working on their own in a practice room then they do with a teacher or coach.
Be your own teacher, learn to analyze your playing, listen very carefully to the sound that you are producing. Every single note is important no matter how fast the passage is. Music is not just notes and scales. It is expression and emotion. Learn to play phrases in the same way that you speak sentences to be expressive. Take advantage of the assets available to you such as dynamics, note lengths and vibrato in order to express yourself.  Be extremely conscientious of your intonation. Spend 90% of your practice time on the things that don’t sound great, slowly and analytically, and 10% putting it all together so that it sounds simple.
Pierre Holstein