It has been said that 10,000 hours of practice are necessary to master any given skill. But people who have studied how humans develop skills have come to a slightly different conclusion. They have found mindful practice to be more important than the sheer number of hours of practice.
What is your mind full of when you’re practicing mindfully? The main thing is your concept of the instrument. Each time you push air into the instrument, you should be thinking consciously about exactly what sounds you want to emerge from the bell.
That includes factors such as your posture and breathing, the timbre (quality of sound), pitch precision, envelope of the sound, articulation, vibrato (or not), clean transitions between notes, phrasing, and style of the music. When you play, you are consciously comparing the result with your intentions.
A private teacher can help you understand what to listen for and how to address any issues with your sound, technic, breathing, and other details.