About dis- and -satisfaction

"Feeling dissatisfied motivates us to practice and improve or change or advance until we once again feel somewhat satisfied - and the process continues, ad infinitum" - I've read some chapters of trombonist Hal Crook's new book* in the past few days.
Basically he says that satisfaction cannot exist without dissatisfaction, and while dissatisfaction can lead to frustration or anxiety, it is also a pushing factor. Of course this sounds painfully obvious. But let me tell you, as a beginner in jazz improvisation, there is just so much to be dissatisfied with, it's overwhelming, like timing and rhythm, hearing ability, melodic and harmonic concepts, accompaniment, musical development, voicings, etc., etc. What people like me (who are always thinking too much, instead of just doing it) need to do is to find a way to live with dissatisfaction, because it's always going to be a partner in our musical careers. There is always going to be a weak point, or a person who plays better or differently. I always thought that I would one day reach a level when I would approve of my playing, being able to do certain basic things, which would allow me to present myself as a musician equal to hundreds of others, one of them - still wanting to improve, but basically doing ok. After two years of intense studies at the jazz school I'm not so sure when I will reach this point. When something is mastered, there are already a hundred new topics a-waiting. I guess I can say that I am doing well, I get good grades, but I often think that I am so far away from being an individual musician who ought to get on stage.
After reading Hal Crook, I got the feeling that maybe there is a line that needs to be drawn. A line between dissatisfaction and satisfaction, which in fact would define self-confidence. For me, it would maybe sound like that: "Yes, there is a lot to be learnt and practised, and it's good to be aware of that, however, look back on the past few years and start to realize how far you've come (better start doin' that or I'll slap you)".
For example: two months ago, I wasn't really able to improvise freely in 5/4, 7/4 or 11/8. Next monday, I'll play two oddmeter tunes in a concert and in my piano exam on Wednesday, I'll play a solo piece in 5/4. Which means that I am on my way, I guess!

A little picture to lighten the once again philosophical mood: I played a little concert in the basement of a house full of musicians last week. And of course said musicians don't have a normal guestroom with a bed, a nightstand and a lovely flowery lamp - this is where I slept. I've never slept in the same room with a steinway AND a drum (and a blanket with a giant burn mark) before! Cozy and a little scary at the same time...

*"Beyond time and changes: a musician's guide to FREE jazz improvisation", Hal Crook, 2010.