I have attention issues. Any time I become conscious of what I'm doing, my chances of f***ing up rocket. At best I look to the audience like like an ape trying to work out algebra. At worst I lose the rhythm completely, or miss the first beat, or embark on an ill-advised and needless fill, or even produce no sound whatsoever for whole seconds at a time, then start up again in the wrong key.
So instead, I try to go by feel and hope that most of the notes work. As people above have noted, you need to know where the changes come to do this confidently, but that's not the same as being note perfect. Bum notes are sometimes bad, often inconsequential; bum grooves and missed beats are way worse.
My last band was highly improvisational, by which I mean that half the time the guy who wrote the songs would forget bits, or randomly change the structure without realising, and we became used to working around that.
Listening to recordings helped me a great deal – you can immediately hear what works and doesn't work, things that on the night went unnoticed by all. It also gives you chance to properly hear what everyone else is doing, and think about how you can better support that. You can then work out your changes at leisure, without having to simultaneously hold down a groove.
Most of all, though, it's the way the song feels that people really respond to, way more than the bassist's consistently perfect note choice. So I learned to empty my head of everything but that. I practise often enough to keep the tunes 'under my fingers', to feel the cues subconsciously so I don't have to think about them. That's very different from rehearsing songs repeatedly in search of note-perfectness, because that's just setting myself up to fail.
All of which is kind of the same thing everyone else has said, plus get a £75 digital recorder and listen back.
Clearly if you're applying to the LPO, it's definitely best to ignore me. Maybe ask your GP about beta-blockers instead.