[quote name='discreet' timestamp='1405427542' post='2501780']
No-one sprang fully-formed from a riven oak one stormy night and was immediately able to play bass flawlessly, all the time. The road to great bass playing is paved with mistakes, self-doubt and lots and lots of practice.
[/quote]
It's worth bearing in mind that this is true of any endeavour.
I'm very much in the OP's shoes - I feel I should be a much better bass player than I am, but I've never been booted out of a band for being a poor player and people ask me to play bass on their recordings now and again, so I can't be awful !!
I'd say don't try an be 'a better bass player' - try and be good at one thing at a time.
Choose a song you like and think is challenging (one of those "I'll never be that good" tunes), and learn it. Learn it inside out.
Then think about what you just did....you taught yourself a tough song - one that impresses [i]you[/i]. You're now a more impressive player [i]by your own standards[/i]...have a break, enjoy your success and then move onto the next tough tune, or bit of technique.